diff --git a/configure.ac b/configure.ac
index b49914343..989162280 100644
--- a/configure.ac
+++ b/configure.ac
@@ -223,11 +223,11 @@ AC_PROG_LN_S
 #   -Wall                        CC, CXX
 #
 
-PROSPECTIVE_CFLAGS="-Wall"
-PROSPECTIVE_CXXFLAGS=""
+PROSPECTIVE_CFLAGS="-Wall -std=c99 -pedantic-errors"
+PROSPECTIVE_CXXFLAGS="-Wall"
 
 AX_CHECK_COMPILER_OPTIONS([C],   ${PROSPECTIVE_CFLAGS})
-AX_CHECK_COMPILER_OPTIONS([C++], ${PROSPECTIVE_CFLAGS} ${PROSPECTIVE_CXXFLAGS})
+AX_CHECK_COMPILER_OPTIONS([C++], ${PROSPECTIVE_CXXFLAGS})
 
 # Check for and initialize libtool
 
diff --git a/examples/cc2538/platform/startup-gcc.c b/examples/cc2538/platform/startup-gcc.c
index 90a512992..662f78462 100644
--- a/examples/cc2538/platform/startup-gcc.c
+++ b/examples/cc2538/platform/startup-gcc.c
@@ -47,7 +47,7 @@ extern uint8_t _einit_array;
 __extension__ typedef int __guard __attribute__((mode(__DI__)));
 int __cxa_guard_acquire(__guard *g) { return !*(char *)(g); }
 void __cxa_guard_release(__guard *g) { *(char *)g = 1; }
-void __cxa_guard_abort(__guard *g) {};
+void __cxa_guard_abort(__guard *g) {}
 void __cxa_pure_virtual(void) { while (1); }
 
 void IntDefaultHandler(void);
diff --git a/examples/posix/platform/Makefile.am b/examples/posix/platform/Makefile.am
index df675c81d..225d39bab 100644
--- a/examples/posix/platform/Makefile.am
+++ b/examples/posix/platform/Makefile.am
@@ -35,9 +35,9 @@ libopenthread_posix_a_CPPFLAGS            = \
     -I$(top_srcdir)/src                     \
     -I$(top_srcdir)/src/core                \
     -I$(top_srcdir)/examples/posix/platform \
+    -D_GNU_SOURCE                           \
     $(NULL)
 
-
 libopenthread_posix_a_SOURCES             = \
     alarm.c                                 \
     logging.c                               \
diff --git a/examples/posix/platform/radio.c b/examples/posix/platform/radio.c
index d812fe4b3..885bf1633 100644
--- a/examples/posix/platform/radio.c
+++ b/examples/posix/platform/radio.c
@@ -482,7 +482,7 @@ int radioTransmit(void)
 {
     struct sockaddr_in sockaddr;
     int rval = 0;
-    int i;
+    uint32_t i;
 
     memset(&sockaddr, 0, sizeof(sockaddr));
     sockaddr.sin_family = AF_INET;
@@ -564,7 +564,7 @@ void posixPlatformRadioProcess(void)
 void radioSendAck(void)
 {
     struct sockaddr_in sockaddr;
-    int i;
+    uint32_t i;
 
     s_ack_frame.mLength = IEEE802154_ACK_LENGTH;
     s_ack_message.mPsdu[0] = IEEE802154_FRAME_TYPE_ACK;
diff --git a/include/openthread-types.h b/include/openthread-types.h
index 627b176cb..c0fdb9619 100644
--- a/include/openthread-types.h
+++ b/include/openthread-types.h
@@ -153,7 +153,7 @@ typedef struct otActiveScanResult
     uint8_t        mChannel;         ///< IEEE 802.15.4 Channel
     int8_t         mRssi;            ///< RSSI (dBm)
     uint8_t        mLqi;             ///< LQI
-    uint8_t        mVersion : 4;     ///< Version
+    unsigned int   mVersion : 4;     ///< Version
     bool           mIsNative : 1;    ///< Native Commissioner flag
     bool           mIsJoinable : 1;  ///< Joining Permitted flag
 } otActiveScanResult;
@@ -188,22 +188,22 @@ typedef struct otLinkModeConfig
     /**
      * 1, if the sender has its receiver on when not transmitting.  0, otherwise.
      */
-    uint8_t mRxOnWhenIdle : 1;
+    bool mRxOnWhenIdle : 1;
 
     /**
      * 1, if the sender will use IEEE 802.15.4 to secure all data requests.  0, otherwise.
      */
-    uint8_t mSecureDataRequests : 1;
+    bool mSecureDataRequests : 1;
 
     /**
      * 1, if the sender is an FFD.  0, otherwise.
      */
-    uint8_t mDeviceType : 1;
+    bool mDeviceType : 1;
 
     /**
      * 1, if the sender requires the full Network Data.  0, otherwise.
      */
-    uint8_t mNetworkData : 1;
+    bool mNetworkData : 1;
 } otLinkModeConfig;
 
 /**
@@ -252,10 +252,10 @@ typedef OT_TOOL_PACKED_BEGIN struct otIp6Address
 {
     union
     {
-        uint8_t  m8[kIp6AddressSize];
-        uint16_t m16[kIp6AddressSize / sizeof(uint16_t)];
-        uint32_t m32[kIp6AddressSize / sizeof(uint32_t)];
-    };
+        uint8_t  m8[kIp6AddressSize];                      ///< 8-bit fields
+        uint16_t m16[kIp6AddressSize / sizeof(uint16_t)];  ///< 16-bit fields
+        uint32_t m32[kIp6AddressSize / sizeof(uint32_t)];  ///< 32-bit fields
+    } mFields;                                             ///< IPv6 accessor fields
 } OT_TOOL_PACKED_END otIp6Address;
 
 /**
@@ -280,37 +280,37 @@ typedef struct otBorderRouterConfig
     /**
      * A 2-bit signed integer indicating router preference as defined in RFC 4291.
      */
-    int8_t      mPreference : 2;
+    int mPreference : 2;
 
     /**
      * TRUE, if @p mPrefix is preferred and should e used for address autoconfiguration.  FALSE, otherwise.
      */
-    uint8_t     mSlaacPreferred : 1;
+    bool mSlaacPreferred : 1;
 
     /**
      * TRUE, if @p mPrefix is valid and should be used for address autoconfiguration.  FALSE, otherwise.
      */
-    uint8_t     mSlaacValid : 1;
+    bool mSlaacValid : 1;
 
     /**
      * TRUE, if this border router is a DHCPv6 Agent that supplies IPv6 address configuration.  FALSE, otherwise.
      */
-    uint8_t     mDhcp : 1;
+    bool mDhcp : 1;
 
     /**
      * TRUE, if this border router is a DHCPv6 Agent that supplies other configuration data.  FALSE, otherwise.
      */
-    uint8_t     mConfigure : 1;
+    bool mConfigure : 1;
 
     /**
      * TRUE, if this border router is a default route for @p mPrefix.  FALSE, otherwise.
      */
-    uint8_t     mDefaultRoute : 1;
+    bool mDefaultRoute : 1;
 
     /**
      * TRUE, if this configuration is considered Stable Network Data.  FALSE, otherwise.
      */
-    uint8_t     mStable : 1;
+    bool mStable : 1;
 } otBorderRouterConfig;
 
 /**
@@ -326,12 +326,12 @@ typedef struct otExternalRouteConfig
     /**
      * A 2-bit signed integer indicating router preference as defined in RFC 4291.
      */
-    int8_t      mPreference : 2;
+    int mPreference : 2;
 
     /**
      * TRUE, if this configuration is considered Stable Network Data.  FALSE, otherwise.
      */
-    uint8_t     mStable : 1;
+    bool mStable : 1;
 } otExternalRouteConfig;
 
 /**
diff --git a/src/cli/cli.cpp b/src/cli/cli.cpp
index 9c3cffa8c..e08c333ae 100644
--- a/src/cli/cli.cpp
+++ b/src/cli/cli.cpp
@@ -332,10 +332,14 @@ void Interpreter::ProcessIpAddr(int argc, char *argv[])
         for (const otNetifAddress *addr = otGetUnicastAddresses(); addr; addr = addr->mNext)
         {
             sServer->OutputFormat("%x:%x:%x:%x:%x:%x:%x:%x\r\n",
-                                  HostSwap16(addr->mAddress.m16[0]), HostSwap16(addr->mAddress.m16[1]),
-                                  HostSwap16(addr->mAddress.m16[2]), HostSwap16(addr->mAddress.m16[3]),
-                                  HostSwap16(addr->mAddress.m16[4]), HostSwap16(addr->mAddress.m16[5]),
-                                  HostSwap16(addr->mAddress.m16[6]), HostSwap16(addr->mAddress.m16[7]));
+                                  HostSwap16(addr->mAddress.mFields.m16[0]),
+                                  HostSwap16(addr->mAddress.mFields.m16[1]),
+                                  HostSwap16(addr->mAddress.mFields.m16[2]),
+                                  HostSwap16(addr->mAddress.mFields.m16[3]),
+                                  HostSwap16(addr->mAddress.mFields.m16[4]),
+                                  HostSwap16(addr->mAddress.mFields.m16[5]),
+                                  HostSwap16(addr->mAddress.mFields.m16[6]),
+                                  HostSwap16(addr->mAddress.mFields.m16[7]));
         }
     }
     else
@@ -558,10 +562,14 @@ void Interpreter::HandleEchoResponse(void *aContext, Message &aMessage, const Ip
 
     sServer->OutputFormat("%d bytes from ", aMessage.GetLength() - aMessage.GetOffset());
     sServer->OutputFormat("%x:%x:%x:%x:%x:%x:%x:%x",
-                          HostSwap16(aMessageInfo.GetPeerAddr().m16[0]), HostSwap16(aMessageInfo.GetPeerAddr().m16[1]),
-                          HostSwap16(aMessageInfo.GetPeerAddr().m16[2]), HostSwap16(aMessageInfo.GetPeerAddr().m16[3]),
-                          HostSwap16(aMessageInfo.GetPeerAddr().m16[4]), HostSwap16(aMessageInfo.GetPeerAddr().m16[5]),
-                          HostSwap16(aMessageInfo.GetPeerAddr().m16[6]), HostSwap16(aMessageInfo.GetPeerAddr().m16[7]));
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[0]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[1]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[2]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[3]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[4]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[5]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[6]),
+                          HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[7]));
     sServer->OutputFormat(": icmp_seq=%d hlim=%d\r\n", icmp6Header.GetSequence(), aMessageInfo.mHopLimit);
 }
 
diff --git a/src/core/net/ip6.cpp b/src/core/net/ip6.cpp
index d5b2a0ebd..673cdbc26 100644
--- a/src/core/net/ip6.cpp
+++ b/src/core/net/ip6.cpp
@@ -77,7 +77,7 @@ uint16_t Ip6::UpdateChecksum(uint16_t checksum, const void *buf, uint16_t len)
 
 uint16_t Ip6::UpdateChecksum(uint16_t checksum, const Address &address)
 {
-    return Ip6::UpdateChecksum(checksum, address.m8, sizeof(address));
+    return Ip6::UpdateChecksum(checksum, address.mFields.m8, sizeof(address));
 }
 
 uint16_t Ip6::ComputePseudoheaderChecksum(const Address &src, const Address &dst, uint16_t length, IpProto proto)
@@ -105,7 +105,7 @@ ThreadError AddMplOption(Message &message, Header &header, IpProto nextHeader, u
 
     hbhHeader.SetNextHeader(nextHeader);
     hbhHeader.SetLength(0);
-    sMpl.InitOption(mplOption, HostSwap16(header.GetSource().m16[7]));
+    sMpl.InitOption(mplOption, HostSwap16(header.GetSource().mFields.m16[7]));
     SuccessOrExit(error = message.Prepend(&mplOption, sizeof(mplOption)));
     SuccessOrExit(error = message.Prepend(&hbhHeader, sizeof(hbhHeader)));
     header.SetPayloadLength(sizeof(hbhHeader) + sizeof(mplOption) + payloadLength);
diff --git a/src/core/net/ip6_address.cpp b/src/core/net/ip6_address.cpp
index 532327b28..cdbb83b6a 100644
--- a/src/core/net/ip6_address.cpp
+++ b/src/core/net/ip6_address.cpp
@@ -47,22 +47,22 @@ namespace Ip6 {
 
 bool Address::IsUnspecified(void) const
 {
-    return (m32[0] == 0 && m32[1] == 0 && m32[2] == 0 && m32[3] == 0);
+    return (mFields.m32[0] == 0 && mFields.m32[1] == 0 && mFields.m32[2] == 0 && mFields.m32[3] == 0);
 }
 
 bool Address::IsLoopback(void) const
 {
-    return (m32[0] == 0 && m32[1] == 0 && m32[2] == 0 && m32[3] == HostSwap32(1));
+    return (mFields.m32[0] == 0 && mFields.m32[1] == 0 && mFields.m32[2] == 0 && mFields.m32[3] == HostSwap32(1));
 }
 
 bool Address::IsLinkLocal(void) const
 {
-    return (m8[0] == 0xfe) && ((m8[1] & 0xc0) == 0x80);
+    return (mFields.m8[0] == 0xfe) && ((mFields.m8[1] & 0xc0) == 0x80);
 }
 
 bool Address::IsMulticast(void) const
 {
-    return m8[0] == 0xff;
+    return mFields.m8[0] == 0xff;
 }
 
 bool Address::IsLinkLocalMulticast(void) const
@@ -72,14 +72,14 @@ bool Address::IsLinkLocalMulticast(void) const
 
 bool Address::IsLinkLocalAllNodesMulticast(void) const
 {
-    return (m32[0] == HostSwap32(0xff020000) && m32[1] == 0 &&
-            m32[2] == 0 && m32[3] == HostSwap32(0x01));
+    return (mFields.m32[0] == HostSwap32(0xff020000) && mFields.m32[1] == 0 &&
+            mFields.m32[2] == 0 && mFields.m32[3] == HostSwap32(0x01));
 }
 
 bool Address::IsLinkLocalAllRoutersMulticast(void) const
 {
-    return (m32[0] == HostSwap32(0xff020000) && m32[1] == 0 &&
-            m32[2] == 0 && m32[3] == HostSwap32(0x02));
+    return (mFields.m32[0] == HostSwap32(0xff020000) && mFields.m32[1] == 0 &&
+            mFields.m32[2] == 0 && mFields.m32[3] == HostSwap32(0x02));
 }
 
 bool Address::IsRealmLocalMulticast(void) const
@@ -89,48 +89,48 @@ bool Address::IsRealmLocalMulticast(void) const
 
 bool Address::IsRealmLocalAllNodesMulticast(void) const
 {
-    return (m32[0] == HostSwap32(0xff030000) && m32[1] == 0 &&
-            m32[2] == 0 && m32[3] == HostSwap32(0x01));
+    return (mFields.m32[0] == HostSwap32(0xff030000) && mFields.m32[1] == 0 &&
+            mFields.m32[2] == 0 && mFields.m32[3] == HostSwap32(0x01));
 }
 
 bool Address::IsRealmLocalAllRoutersMulticast(void) const
 {
-    return (m32[0] == HostSwap32(0xff030000) && m32[1] == 0 &&
-            m32[2] == 0 && m32[3] == HostSwap32(0x02));
+    return (mFields.m32[0] == HostSwap32(0xff030000) && mFields.m32[1] == 0 &&
+            mFields.m32[2] == 0 && mFields.m32[3] == HostSwap32(0x02));
 }
 
 bool Address::IsRoutingLocator(void) const
 {
-    return (m16[4] == HostSwap16(0x0000) && m16[5] == HostSwap16(0x00ff) &&
-            m16[6] == HostSwap16(0xfe00));
+    return (mFields.m16[4] == HostSwap16(0x0000) && mFields.m16[5] == HostSwap16(0x00ff) &&
+            mFields.m16[6] == HostSwap16(0xfe00));
 }
 
 const uint8_t *Address::GetIid(void) const
 {
-    return m8 + kInterfaceIdentifierOffset;
+    return mFields.m8 + kInterfaceIdentifierOffset;
 }
 
 uint8_t *Address::GetIid(void)
 {
-    return m8 + kInterfaceIdentifierOffset;
+    return mFields.m8 + kInterfaceIdentifierOffset;
 }
 
 void Address::SetIid(const uint8_t *aIid)
 {
-    memcpy(m8 + kInterfaceIdentifierOffset, aIid, kInterfaceIdentifierSize);
+    memcpy(mFields.m8 + kInterfaceIdentifierOffset, aIid, kInterfaceIdentifierSize);
 }
 
 void Address::SetIid(const Mac::ExtAddress &aEui64)
 {
-    memcpy(m8 + kInterfaceIdentifierOffset, aEui64.m8, kInterfaceIdentifierSize);
-    m8[kInterfaceIdentifierOffset] ^= 0x02;
+    memcpy(mFields.m8 + kInterfaceIdentifierOffset, aEui64.m8, kInterfaceIdentifierSize);
+    mFields.m8[kInterfaceIdentifierOffset] ^= 0x02;
 }
 
 uint8_t Address::GetScope(void) const
 {
     if (IsMulticast())
     {
-        return m8[1] & 0xf;
+        return mFields.m8[1] & 0xf;
     }
     else if (IsLinkLocal())
     {
@@ -151,7 +151,7 @@ uint8_t Address::PrefixMatch(const Address &aOther) const
 
     for (uint8_t i = 0; i < sizeof(Address); i++)
     {
-        diff = m8[i] ^ aOther.m8[i];
+        diff = mFields.m8[i] ^ aOther.mFields.m8[i];
 
         if (diff == 0)
         {
@@ -174,19 +174,19 @@ uint8_t Address::PrefixMatch(const Address &aOther) const
 
 bool Address::operator==(const Address &aOther) const
 {
-    return memcmp(m8, aOther.m8, sizeof(m8)) == 0;
+    return memcmp(mFields.m8, aOther.mFields.m8, sizeof(mFields.m8)) == 0;
 }
 
 bool Address::operator!=(const Address &aOther) const
 {
-    return memcmp(m8, aOther.m8, sizeof(m8)) != 0;
+    return memcmp(mFields.m8, aOther.mFields.m8, sizeof(mFields.m8)) != 0;
 }
 
 ThreadError Address::FromString(const char *aBuf)
 {
     ThreadError error = kThreadError_None;
-    uint8_t *dst = reinterpret_cast<uint8_t *>(m8);
-    uint8_t *endp = reinterpret_cast<uint8_t *>(m8 + 15);
+    uint8_t *dst = reinterpret_cast<uint8_t *>(mFields.m8);
+    uint8_t *endp = reinterpret_cast<uint8_t *>(mFields.m8 + 15);
     uint8_t *colonp = NULL;
     uint16_t val = 0;
     uint8_t count = 0;
@@ -194,7 +194,7 @@ ThreadError Address::FromString(const char *aBuf)
     uint8_t ch;
     uint8_t d;
 
-    memset(m8, 0, 16);
+    memset(mFields.m8, 0, 16);
 
     dst--;
 
@@ -258,10 +258,10 @@ exit:
 const char *Address::ToString(char *aBuf, uint16_t aSize) const
 {
     snprintf(aBuf, aSize, "%x:%x:%x:%x:%x:%x:%x:%x",
-             HostSwap16(m16[0]), HostSwap16(m16[1]),
-             HostSwap16(m16[2]), HostSwap16(m16[3]),
-             HostSwap16(m16[4]), HostSwap16(m16[5]),
-             HostSwap16(m16[6]), HostSwap16(m16[7]));
+             HostSwap16(mFields.m16[0]), HostSwap16(mFields.m16[1]),
+             HostSwap16(mFields.m16[2]), HostSwap16(mFields.m16[3]),
+             HostSwap16(mFields.m16[4]), HostSwap16(mFields.m16[5]),
+             HostSwap16(mFields.m16[6]), HostSwap16(mFields.m16[7]));
     return aBuf;
 }
 
diff --git a/src/core/openthread.cpp b/src/core/openthread.cpp
index de060f9b9..c68147fa9 100644
--- a/src/core/openthread.cpp
+++ b/src/core/openthread.cpp
@@ -299,24 +299,26 @@ ThreadError otAddBorderRouter(const otBorderRouterConfig *aConfig)
         flags |= NetworkData::BorderRouterEntry::kDefaultRouteFlag;
     }
 
-    return sThreadNetif->GetNetworkDataLocal().AddOnMeshPrefix(aConfig->mPrefix.mPrefix.m8, aConfig->mPrefix.mLength,
+    return sThreadNetif->GetNetworkDataLocal().AddOnMeshPrefix(aConfig->mPrefix.mPrefix.mFields.m8,
+                                                               aConfig->mPrefix.mLength,
                                                                aConfig->mPreference, flags, aConfig->mStable);
 }
 
 ThreadError otRemoveBorderRouter(const otIp6Prefix *aPrefix)
 {
-    return sThreadNetif->GetNetworkDataLocal().RemoveOnMeshPrefix(aPrefix->mPrefix.m8, aPrefix->mLength);
+    return sThreadNetif->GetNetworkDataLocal().RemoveOnMeshPrefix(aPrefix->mPrefix.mFields.m8, aPrefix->mLength);
 }
 
 ThreadError otAddExternalRoute(const otExternalRouteConfig *aConfig)
 {
-    return sThreadNetif->GetNetworkDataLocal().AddHasRoutePrefix(aConfig->mPrefix.mPrefix.m8, aConfig->mPrefix.mLength,
+    return sThreadNetif->GetNetworkDataLocal().AddHasRoutePrefix(aConfig->mPrefix.mPrefix.mFields.m8,
+                                                                 aConfig->mPrefix.mLength,
                                                                  aConfig->mPreference, aConfig->mStable);
 }
 
 ThreadError otRemoveExternalRoute(const otIp6Prefix *aPrefix)
 {
-    return sThreadNetif->GetNetworkDataLocal().RemoveHasRoutePrefix(aPrefix->mPrefix.m8, aPrefix->mLength);
+    return sThreadNetif->GetNetworkDataLocal().RemoveHasRoutePrefix(aPrefix->mPrefix.mFields.m8, aPrefix->mLength);
 }
 
 ThreadError otSendServerData(void)
diff --git a/src/core/thread/address_resolver.cpp b/src/core/thread/address_resolver.cpp
index 3df28f127..01307df55 100644
--- a/src/core/thread/address_resolver.cpp
+++ b/src/core/thread/address_resolver.cpp
@@ -185,8 +185,8 @@ ThreadError AddressResolver::SendAddressQuery(const Ip6::Address &aEid)
     SuccessOrExit(error = message->Append(&targetTlv, sizeof(targetTlv)));
 
     memset(&messageInfo, 0, sizeof(messageInfo));
-    messageInfo.GetPeerAddr().m16[0] = HostSwap16(0xff03);
-    messageInfo.GetPeerAddr().m16[7] = HostSwap16(0x0002);
+    messageInfo.GetPeerAddr().mFields.m16[0] = HostSwap16(0xff03);
+    messageInfo.GetPeerAddr().mFields.m16[7] = HostSwap16(0x0002);
     messageInfo.mPeerPort = kCoapUdpPort;
     messageInfo.mInterfaceId = mNetif.GetInterfaceId();
 
@@ -230,7 +230,7 @@ void AddressResolver::HandleAddressNotification(Coap::Header &aHeader, Message &
     VerifyOrExit(aHeader.GetType() == Coap::Header::kTypeConfirmable &&
                  aHeader.GetCode() == Coap::Header::kCodePost, ;);
 
-    otLogInfoArp("Received address notification from %04x\n", HostSwap16(aMessageInfo.GetPeerAddr().m16[7]));
+    otLogInfoArp("Received address notification from %04x\n", HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[7]));
 
     SuccessOrExit(ThreadTlv::GetTlv(aMessage, ThreadTlv::kTarget, sizeof(targetTlv), targetTlv));
     VerifyOrExit(targetTlv.IsValid(), ;);
@@ -342,8 +342,8 @@ ThreadError AddressResolver::SendAddressError(const ThreadTargetTlv &aTarget, co
 
     if (aDestination == NULL)
     {
-        messageInfo.GetPeerAddr().m16[0] = HostSwap16(0xff03);
-        messageInfo.GetPeerAddr().m16[7] = HostSwap16(0x0002);
+        messageInfo.GetPeerAddr().mFields.m16[0] = HostSwap16(0xff03);
+        messageInfo.GetPeerAddr().mFields.m16[7] = HostSwap16(0x0002);
     }
     else
     {
@@ -427,7 +427,7 @@ void AddressResolver::HandleAddressError(Coap::Header &aHeader, Message &aMessag
                 memset(&children[i].mIp6Address[j], 0, sizeof(children[i].mIp6Address[j]));
 
                 memset(&destination, 0, sizeof(destination));
-                destination.m16[0] = HostSwap16(0xfe80);
+                destination.mFields.m16[0] = HostSwap16(0xfe80);
                 destination.SetIid(children[i].mMacAddr);
 
                 SendAddressError(targetTlv, mlIidTlv, &destination);
@@ -459,7 +459,7 @@ void AddressResolver::HandleAddressQuery(Coap::Header &aHeader, Message &aMessag
     VerifyOrExit(aHeader.GetType() == Coap::Header::kTypeNonConfirmable &&
                  aHeader.GetCode() == Coap::Header::kCodePost, ;);
 
-    otLogInfoArp("Received address query from %04x\n", HostSwap16(aMessageInfo.GetPeerAddr().m16[7]));
+    otLogInfoArp("Received address query from %04x\n", HostSwap16(aMessageInfo.GetPeerAddr().mFields.m16[7]));
 
     SuccessOrExit(ThreadTlv::GetTlv(aMessage, ThreadTlv::kTarget, sizeof(targetTlv), targetTlv));
     VerifyOrExit(targetTlv.IsValid(), ;);
diff --git a/src/core/thread/lowpan.cpp b/src/core/thread/lowpan.cpp
index 8d49a1b38..a096dc9a4 100644
--- a/src/core/thread/lowpan.cpp
+++ b/src/core/thread/lowpan.cpp
@@ -56,8 +56,8 @@ ThreadError Lowpan::CopyContext(const Context &aContext, Ip6::Address &aAddress)
 
     for (int i = (aContext.mPrefixLength & ~7); i < aContext.mPrefixLength; i++)
     {
-        aAddress.m8[i / CHAR_BIT] &= ~(0x80 >> (i % CHAR_BIT));
-        aAddress.m8[i / CHAR_BIT] |= aContext.mPrefix[i / CHAR_BIT] & (0x80 >> (i % CHAR_BIT));
+        aAddress.mFields.m8[i / CHAR_BIT] &= ~(0x80 >> (i % CHAR_BIT));
+        aAddress.mFields.m8[i / CHAR_BIT] |= aContext.mPrefix[i / CHAR_BIT] & (0x80 >> (i % CHAR_BIT));
     }
 
     return kThreadError_None;
@@ -68,10 +68,10 @@ ThreadError Lowpan::ComputeIid(const Mac::Address &aMacAddr, const Context &aCon
     switch (aMacAddr.mLength)
     {
     case 2:
-        aIpAddress.m16[4] = HostSwap16(0x0000);
-        aIpAddress.m16[5] = HostSwap16(0x00ff);
-        aIpAddress.m16[6] = HostSwap16(0xfe00);
-        aIpAddress.m16[7] = HostSwap16(aMacAddr.mShortAddress);
+        aIpAddress.mFields.m16[4] = HostSwap16(0x0000);
+        aIpAddress.mFields.m16[5] = HostSwap16(0x00ff);
+        aIpAddress.mFields.m16[6] = HostSwap16(0xfe00);
+        aIpAddress.mFields.m16[7] = HostSwap16(aMacAddr.mShortAddress);
         break;
 
     case Ip6::Address::kInterfaceIdentifierSize:
@@ -86,8 +86,8 @@ ThreadError Lowpan::ComputeIid(const Mac::Address &aMacAddr, const Context &aCon
     {
         for (int i = (aContext.mPrefixLength & ~7); i < aContext.mPrefixLength; i++)
         {
-            aIpAddress.m8[i / CHAR_BIT] &= ~(0x80 >> (i % CHAR_BIT));
-            aIpAddress.m8[i / CHAR_BIT] |= aContext.mPrefix[i / CHAR_BIT] & (0x80 >> (i % CHAR_BIT));
+            aIpAddress.mFields.m8[i / CHAR_BIT] &= ~(0x80 >> (i % CHAR_BIT));
+            aIpAddress.mFields.m8[i / CHAR_BIT] |= aContext.mPrefix[i / CHAR_BIT] & (0x80 >> (i % CHAR_BIT));
         }
     }
 
@@ -110,14 +110,14 @@ int Lowpan::CompressSourceIid(const Mac::Address &aMacAddr, const Ip6::Address &
     else
     {
         tmp.mLength = sizeof(tmp.mShortAddress);
-        tmp.mShortAddress = HostSwap16(aIpAddr.m16[7]);
+        tmp.mShortAddress = HostSwap16(aIpAddr.mFields.m16[7]);
         ComputeIid(tmp, aContext, ipaddr);
 
         if (memcmp(ipaddr.GetIid(), aIpAddr.GetIid(), Ip6::Address::kInterfaceIdentifierSize) == 0)
         {
             aHcCtl |= kHcSrcAddrMode2;
-            cur[0] = aIpAddr.m8[14];
-            cur[1] = aIpAddr.m8[15];
+            cur[0] = aIpAddr.mFields.m8[14];
+            cur[1] = aIpAddr.mFields.m8[15];
             cur += 2;
         }
         else
@@ -147,14 +147,14 @@ int Lowpan::CompressDestinationIid(const Mac::Address &aMacAddr, const Ip6::Addr
     else
     {
         tmp.mLength = sizeof(tmp.mShortAddress);
-        tmp.mShortAddress = HostSwap16(aIpAddr.m16[7]);
+        tmp.mShortAddress = HostSwap16(aIpAddr.mFields.m16[7]);
         ComputeIid(tmp, aContext, ipaddr);
 
         if (memcmp(ipaddr.GetIid(), aIpAddr.GetIid(), Ip6::Address::kInterfaceIdentifierSize) == 0)
         {
             aHcCtl |= kHcDstAddrMode2;
-            cur[0] = aIpAddr.m8[14];
-            cur[1] = aIpAddr.m8[15];
+            cur[0] = aIpAddr.mFields.m8[14];
+            cur[1] = aIpAddr.mFields.m8[15];
             cur += 2;
         }
         else
@@ -176,31 +176,31 @@ int Lowpan::CompressMulticast(const Ip6::Address &aIpAddr, uint16_t &aHcCtl, uin
 
     for (unsigned int i = 2; i < sizeof(Ip6::Address); i++)
     {
-        if (aIpAddr.m8[i])
+        if (aIpAddr.mFields.m8[i])
         {
-            if (aIpAddr.m8[1] == 0x02 && i >= 15)
+            if (aIpAddr.mFields.m8[1] == 0x02 && i >= 15)
             {
                 aHcCtl |= kHcDstAddrMode3;
-                cur[0] = aIpAddr.m8[15];
+                cur[0] = aIpAddr.mFields.m8[15];
                 cur++;
             }
             else if (i >= 13)
             {
                 aHcCtl |= kHcDstAddrMode2;
-                cur[0] = aIpAddr.m8[1];
-                memcpy(cur + 1, aIpAddr.m8 + 13, 3);
+                cur[0] = aIpAddr.mFields.m8[1];
+                memcpy(cur + 1, aIpAddr.mFields.m8 + 13, 3);
                 cur += 4;
             }
             else if (i >= 9)
             {
                 aHcCtl |= kHcDstAddrMode1;
-                cur[0] = aIpAddr.m8[1];
-                memcpy(cur + 1, aIpAddr.m8 + 11, 5);
+                cur[0] = aIpAddr.mFields.m8[1];
+                memcpy(cur + 1, aIpAddr.mFields.m8 + 11, 5);
                 cur += 6;
             }
             else
             {
-                memcpy(cur, aIpAddr.m8, sizeof(Ip6::Address));
+                memcpy(cur, aIpAddr.mFields.m8, sizeof(Ip6::Address));
                 cur += sizeof(Ip6::Address);
             }
 
@@ -330,7 +330,7 @@ int Lowpan::Compress(Message &aMessage, const Mac::Address &aMacSource, const Ma
     }
     else
     {
-        memcpy(cur, ip6Header.GetSource().m8, sizeof(ip6Header.GetSource()));
+        memcpy(cur, ip6Header.GetSource().mFields.m8, sizeof(ip6Header.GetSource()));
         cur += sizeof(Ip6::Address);
     }
 
@@ -591,9 +591,9 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
         break;
 
     case kHcSrcAddrMode2:
-        ip6Header.GetSource().m8[11] = 0xff;
-        ip6Header.GetSource().m8[12] = 0xfe;
-        memcpy(ip6Header.GetSource().m8 + 14, cur, 2);
+        ip6Header.GetSource().mFields.m8[11] = 0xff;
+        ip6Header.GetSource().mFields.m8[12] = 0xfe;
+        memcpy(ip6Header.GetSource().mFields.m8 + 14, cur, 2);
         cur += 2;
         break;
 
@@ -606,7 +606,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
     {
         if ((hcCtl & kHcSrcAddrModeMask) != 0)
         {
-            ip6Header.GetSource().m16[0] = HostSwap16(0xfe80);
+            ip6Header.GetSource().mFields.m16[0] = HostSwap16(0xfe80);
         }
     }
     else
@@ -632,9 +632,9 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
             break;
 
         case kHcDstAddrMode2:
-            ip6Header.GetDestination().m8[11] = 0xff;
-            ip6Header.GetDestination().m8[12] = 0xfe;
-            memcpy(ip6Header.GetDestination().m8 + 14, cur, 2);
+            ip6Header.GetDestination().mFields.m8[11] = 0xff;
+            ip6Header.GetDestination().mFields.m8[12] = 0xfe;
+            memcpy(ip6Header.GetDestination().mFields.m8 + 14, cur, 2);
             cur += 2;
             break;
 
@@ -647,7 +647,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
         {
             if ((hcCtl & kHcDstAddrModeMask) != 0)
             {
-                ip6Header.GetDestination().m16[0] = HostSwap16(0xfe80);
+                ip6Header.GetDestination().mFields.m16[0] = HostSwap16(0xfe80);
             }
         }
         else
@@ -660,32 +660,32 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
     {
         // Multicast Destination Address
 
-        ip6Header.GetDestination().m8[0] = 0xff;
+        ip6Header.GetDestination().mFields.m8[0] = 0xff;
 
         if ((hcCtl & kHcDstAddrContext) == 0)
         {
             switch (hcCtl & kHcDstAddrModeMask)
             {
             case kHcDstAddrMode0:
-                memcpy(ip6Header.GetDestination().m8, cur, sizeof(Ip6::Address));
+                memcpy(ip6Header.GetDestination().mFields.m8, cur, sizeof(Ip6::Address));
                 cur += sizeof(Ip6::Address);
                 break;
 
             case kHcDstAddrMode1:
-                ip6Header.GetDestination().m8[1] = cur[0];
-                memcpy(ip6Header.GetDestination().m8 + 11, cur + 1, 5);
+                ip6Header.GetDestination().mFields.m8[1] = cur[0];
+                memcpy(ip6Header.GetDestination().mFields.m8 + 11, cur + 1, 5);
                 cur += 6;
                 break;
 
             case kHcDstAddrMode2:
-                ip6Header.GetDestination().m8[1] = cur[0];
-                memcpy(ip6Header.GetDestination().m8 + 13, cur + 1, 3);
+                ip6Header.GetDestination().mFields.m8[1] = cur[0];
+                memcpy(ip6Header.GetDestination().mFields.m8 + 13, cur + 1, 3);
                 cur += 4;
                 break;
 
             case kHcDstAddrMode3:
-                ip6Header.GetDestination().m8[1] = 0x02;
-                ip6Header.GetDestination().m8[15] = cur[0];
+                ip6Header.GetDestination().mFields.m8[1] = 0x02;
+                ip6Header.GetDestination().mFields.m8[15] = cur[0];
                 cur++;
                 break;
             }
@@ -696,11 +696,11 @@ int Lowpan::DecompressBaseHeader(Ip6::Header &ip6Header, const Mac::Address &aMa
             {
             case 0:
                 VerifyOrExit(dstContextValid, error = kThreadError_Parse);
-                ip6Header.GetDestination().m8[1] = cur[0];
-                ip6Header.GetDestination().m8[2] = cur[1];
-                ip6Header.GetDestination().m8[3] = dstContext.mPrefixLength;
-                memcpy(ip6Header.GetDestination().m8 + 4, dstContext.mPrefix, 8);
-                memcpy(ip6Header.GetDestination().m8 + 12, cur + 2, 4);
+                ip6Header.GetDestination().mFields.m8[1] = cur[0];
+                ip6Header.GetDestination().mFields.m8[2] = cur[1];
+                ip6Header.GetDestination().mFields.m8[3] = dstContext.mPrefixLength;
+                memcpy(ip6Header.GetDestination().mFields.m8 + 4, dstContext.mPrefix, 8);
+                memcpy(ip6Header.GetDestination().mFields.m8 + 12, cur + 2, 4);
                 cur += 6;
                 break;
 
diff --git a/src/core/thread/mesh_forwarder.cpp b/src/core/thread/mesh_forwarder.cpp
index c38883670..8d259df39 100644
--- a/src/core/thread/mesh_forwarder.cpp
+++ b/src/core/thread/mesh_forwarder.cpp
@@ -470,7 +470,7 @@ ThreadError MeshForwarder::UpdateIp6Route(Message &aMessage)
             // FFD - peform full routing
             if (mMle.IsRoutingLocator(ip6Header.GetDestination()))
             {
-                rloc16 = HostSwap16(ip6Header.GetDestination().m16[7]);
+                rloc16 = HostSwap16(ip6Header.GetDestination().mFields.m16[7]);
                 VerifyOrExit(mMle.GetRouterId(rloc16) < Mle::kMaxRouterId, error = kThreadError_Drop);
                 mMeshDest = rloc16;
             }
@@ -608,21 +608,21 @@ ThreadError MeshForwarder::GetMacDestinationAddress(const Ip6::Address &aIp6Addr
         aMacAddr.mLength = sizeof(aMacAddr.mShortAddress);
         aMacAddr.mShortAddress = Mac::kShortAddrBroadcast;
     }
-    else if (aIp6Addr.m16[0] == HostSwap16(0xfe80) &&
-             aIp6Addr.m16[1] == HostSwap16(0x0000) &&
-             aIp6Addr.m16[2] == HostSwap16(0x0000) &&
-             aIp6Addr.m16[3] == HostSwap16(0x0000) &&
-             aIp6Addr.m16[4] == HostSwap16(0x0000) &&
-             aIp6Addr.m16[5] == HostSwap16(0x00ff) &&
-             aIp6Addr.m16[6] == HostSwap16(0xfe00))
+    else if (aIp6Addr.mFields.m16[0] == HostSwap16(0xfe80) &&
+             aIp6Addr.mFields.m16[1] == HostSwap16(0x0000) &&
+             aIp6Addr.mFields.m16[2] == HostSwap16(0x0000) &&
+             aIp6Addr.mFields.m16[3] == HostSwap16(0x0000) &&
+             aIp6Addr.mFields.m16[4] == HostSwap16(0x0000) &&
+             aIp6Addr.mFields.m16[5] == HostSwap16(0x00ff) &&
+             aIp6Addr.mFields.m16[6] == HostSwap16(0xfe00))
     {
         aMacAddr.mLength = sizeof(aMacAddr.mShortAddress);
-        aMacAddr.mShortAddress = HostSwap16(aIp6Addr.m16[7]);
+        aMacAddr.mShortAddress = HostSwap16(aIp6Addr.mFields.m16[7]);
     }
     else if (mMle.IsRoutingLocator(aIp6Addr))
     {
         aMacAddr.mLength = sizeof(aMacAddr.mShortAddress);
-        aMacAddr.mShortAddress = HostSwap16(aIp6Addr.m16[7]);
+        aMacAddr.mShortAddress = HostSwap16(aIp6Addr.mFields.m16[7]);
     }
     else
     {
@@ -991,14 +991,14 @@ void MeshForwarder::HandleReceivedFrame(Mac::Frame &aFrame, ThreadError aError)
     if (aError == kThreadError_Security)
     {
         memset(&destination, 0, sizeof(destination));
-        destination.m16[0] = HostSwap16(0xfe80);
+        destination.mFields.m16[0] = HostSwap16(0xfe80);
 
         switch (macSource.mLength)
         {
         case 2:
-            destination.m16[5] = HostSwap16(0x00ff);
-            destination.m16[6] = HostSwap16(0xfe00);
-            destination.m16[7] = HostSwap16(macSource.mShortAddress);
+            destination.mFields.m16[5] = HostSwap16(0x00ff);
+            destination.mFields.m16[6] = HostSwap16(0xfe00);
+            destination.mFields.m16[7] = HostSwap16(macSource.mShortAddress);
             break;
 
         case 8:
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index d02f9bdcd..6db7e42c8 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -82,7 +82,7 @@ Mle::Mle(ThreadNetif &aThreadNetif) :
 
     // link-local 64
     memset(&mLinkLocal64, 0, sizeof(mLinkLocal64));
-    mLinkLocal64.GetAddress().m16[0] = HostSwap16(0xfe80);
+    mLinkLocal64.GetAddress().mFields.m16[0] = HostSwap16(0xfe80);
     mLinkLocal64.GetAddress().SetIid(*mMac.GetExtAddress());
     mLinkLocal64.mPrefixLength = 64;
     mLinkLocal64.mPreferredLifetime = 0xffffffff;
@@ -91,48 +91,48 @@ Mle::Mle(ThreadNetif &aThreadNetif) :
 
     // link-local 16
     memset(&mLinkLocal16, 0, sizeof(mLinkLocal16));
-    mLinkLocal16.GetAddress().m16[0] = HostSwap16(0xfe80);
-    mLinkLocal16.GetAddress().m16[5] = HostSwap16(0x00ff);
-    mLinkLocal16.GetAddress().m16[6] = HostSwap16(0xfe00);
+    mLinkLocal16.GetAddress().mFields.m16[0] = HostSwap16(0xfe80);
+    mLinkLocal16.GetAddress().mFields.m16[5] = HostSwap16(0x00ff);
+    mLinkLocal16.GetAddress().mFields.m16[6] = HostSwap16(0xfe00);
     mLinkLocal16.mPrefixLength = 64;
     mLinkLocal16.mPreferredLifetime = 0xffffffff;
     mLinkLocal16.mValidLifetime = 0xffffffff;
 
     // initialize Mesh Local Prefix
-    mMeshLocal64.GetAddress().m8[0] = 0xfd;
-    memcpy(mMeshLocal64.GetAddress().m8 + 1, mMac.GetExtendedPanId(), 5);
-    mMeshLocal64.GetAddress().m8[6] = 0x00;
-    mMeshLocal64.GetAddress().m8[7] = 0x00;
+    mMeshLocal64.GetAddress().mFields.m8[0] = 0xfd;
+    memcpy(mMeshLocal64.GetAddress().mFields.m8 + 1, mMac.GetExtendedPanId(), 5);
+    mMeshLocal64.GetAddress().mFields.m8[6] = 0x00;
+    mMeshLocal64.GetAddress().mFields.m8[7] = 0x00;
 
     // mesh-local 64
     for (int i = 8; i < 16; i++)
     {
-        mMeshLocal64.GetAddress().m8[i] = otPlatRandomGet();
+        mMeshLocal64.GetAddress().mFields.m8[i] = otPlatRandomGet();
     }
 
     mMeshLocal64.mPrefixLength = 64;
     mMeshLocal64.mPreferredLifetime = 0xffffffff;
     mMeshLocal64.mValidLifetime = 0xffffffff;
-    SetMeshLocalPrefix(mMeshLocal64.GetAddress().m8); // Also calls AddUnicastAddress
+    SetMeshLocalPrefix(mMeshLocal64.GetAddress().mFields.m8); // Also calls AddUnicastAddress
 
     // mesh-local 16
-    mMeshLocal16.GetAddress().m16[4] = HostSwap16(0x0000);
-    mMeshLocal16.GetAddress().m16[5] = HostSwap16(0x00ff);
-    mMeshLocal16.GetAddress().m16[6] = HostSwap16(0xfe00);
+    mMeshLocal16.GetAddress().mFields.m16[4] = HostSwap16(0x0000);
+    mMeshLocal16.GetAddress().mFields.m16[5] = HostSwap16(0x00ff);
+    mMeshLocal16.GetAddress().mFields.m16[6] = HostSwap16(0xfe00);
     mMeshLocal16.mPrefixLength = 64;
     mMeshLocal16.mPreferredLifetime = 0xffffffff;
     mMeshLocal16.mValidLifetime = 0xffffffff;
 
     // link-local all thread nodes
-    mLinkLocalAllThreadNodes.GetAddress().m16[0] = HostSwap16(0xff32);
-    mLinkLocalAllThreadNodes.GetAddress().m16[6] = HostSwap16(0x0000);
-    mLinkLocalAllThreadNodes.GetAddress().m16[7] = HostSwap16(0x0001);
+    mLinkLocalAllThreadNodes.GetAddress().mFields.m16[0] = HostSwap16(0xff32);
+    mLinkLocalAllThreadNodes.GetAddress().mFields.m16[6] = HostSwap16(0x0000);
+    mLinkLocalAllThreadNodes.GetAddress().mFields.m16[7] = HostSwap16(0x0001);
     mNetif.SubscribeMulticast(mLinkLocalAllThreadNodes);
 
     // realm-local all thread nodes
-    mRealmLocalAllThreadNodes.GetAddress().m16[0] = HostSwap16(0xff33);
-    mRealmLocalAllThreadNodes.GetAddress().m16[6] = HostSwap16(0x0000);
-    mRealmLocalAllThreadNodes.GetAddress().m16[7] = HostSwap16(0x0001);
+    mRealmLocalAllThreadNodes.GetAddress().mFields.m16[0] = HostSwap16(0xff33);
+    mRealmLocalAllThreadNodes.GetAddress().mFields.m16[6] = HostSwap16(0x0000);
+    mRealmLocalAllThreadNodes.GetAddress().mFields.m16[7] = HostSwap16(0x0001);
     mNetif.SubscribeMulticast(mRealmLocalAllThreadNodes);
 
     mNetifCallback.Set(&HandleNetifStateChanged, this);
@@ -345,7 +345,7 @@ exit:
 
 const uint8_t *Mle::GetMeshLocalPrefix(void) const
 {
-    return mMeshLocal16.GetAddress().m8;
+    return mMeshLocal16.GetAddress().mFields.m8;
 }
 
 ThreadError Mle::SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
@@ -354,14 +354,14 @@ ThreadError Mle::SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
     mNetif.RemoveUnicastAddress(mMeshLocal64);
     mNetif.RemoveUnicastAddress(mMeshLocal16);
 
-    memcpy(mMeshLocal64.GetAddress().m8, aMeshLocalPrefix, 8);
-    memcpy(mMeshLocal16.GetAddress().m8, mMeshLocal64.GetAddress().m8, 8);
+    memcpy(mMeshLocal64.GetAddress().mFields.m8, aMeshLocalPrefix, 8);
+    memcpy(mMeshLocal16.GetAddress().mFields.m8, mMeshLocal64.GetAddress().mFields.m8, 8);
 
-    mLinkLocalAllThreadNodes.GetAddress().m8[3] = 64;
-    memcpy(mLinkLocalAllThreadNodes.GetAddress().m8 + 4, mMeshLocal64.GetAddress().m8, 8);
+    mLinkLocalAllThreadNodes.GetAddress().mFields.m8[3] = 64;
+    memcpy(mLinkLocalAllThreadNodes.GetAddress().mFields.m8 + 4, mMeshLocal64.GetAddress().mFields.m8, 8);
 
-    mRealmLocalAllThreadNodes.GetAddress().m8[3] = 64;
-    memcpy(mRealmLocalAllThreadNodes.GetAddress().m8 + 4, mMeshLocal64.GetAddress().m8, 8);
+    mRealmLocalAllThreadNodes.GetAddress().mFields.m8[3] = 64;
+    memcpy(mRealmLocalAllThreadNodes.GetAddress().mFields.m8 + 4, mMeshLocal64.GetAddress().mFields.m8, 8);
 
     // Add the address back into the table.
     mNetif.AddUnicastAddress(mMeshLocal64);
@@ -410,11 +410,11 @@ ThreadError Mle::SetRloc16(uint16_t aRloc16)
     if (aRloc16 != Mac::kShortAddrInvalid)
     {
         // link-local 16
-        mLinkLocal16.GetAddress().m16[7] = HostSwap16(aRloc16);
+        mLinkLocal16.GetAddress().mFields.m16[7] = HostSwap16(aRloc16);
         mNetif.AddUnicastAddress(mLinkLocal16);
 
         // mesh-local 16
-        mMeshLocal16.GetAddress().m16[7] = HostSwap16(aRloc16);
+        mMeshLocal16.GetAddress().mFields.m16[7] = HostSwap16(aRloc16);
         mNetif.AddUnicastAddress(mMeshLocal16);
     }
 
@@ -457,10 +457,10 @@ ThreadError Mle::GetLeaderAddress(Ip6::Address &aAddress) const
     VerifyOrExit(GetRloc16() != Mac::kShortAddrInvalid, error = kThreadError_Detached);
 
     memcpy(&aAddress, &mMeshLocal16.GetAddress(), 8);
-    aAddress.m16[4] = HostSwap16(0x0000);
-    aAddress.m16[5] = HostSwap16(0x00ff);
-    aAddress.m16[6] = HostSwap16(0xfe00);
-    aAddress.m16[7] = HostSwap16(GetRloc16(mLeaderData.GetLeaderRouterId()));
+    aAddress.mFields.m16[4] = HostSwap16(0x0000);
+    aAddress.mFields.m16[5] = HostSwap16(0x00ff);
+    aAddress.mFields.m16[6] = HostSwap16(0xfe00);
+    aAddress.mFields.m16[7] = HostSwap16(GetRloc16(mLeaderData.GetLeaderRouterId()));
 
 exit:
     return error;
@@ -747,7 +747,7 @@ void Mle::HandleNetifStateChanged(uint32_t aFlags)
         // Mesh Local EID was removed, choose a new one and add it back
         for (int i = 8; i < 16; i++)
         {
-            mMeshLocal64.GetAddress().m8[i] = otPlatRandomGet();
+            mMeshLocal64.GetAddress().mFields.m8[i] = otPlatRandomGet();
         }
 
         mNetif.AddUnicastAddress(mMeshLocal64);
@@ -916,8 +916,8 @@ ThreadError Mle::SendParentRequest(void)
     SuccessOrExit(error = AppendVersion(*message));
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xff02);
-    destination.m16[7] = HostSwap16(0x0002);
+    destination.mFields.m16[0] = HostSwap16(0xff02);
+    destination.mFields.m16[7] = HostSwap16(0x0002);
     SuccessOrExit(error = SendMessage(*message, destination));
 
     switch (mParentRequestState)
@@ -970,7 +970,7 @@ ThreadError Mle::SendChildIdRequest(void)
     SuccessOrExit(error = AppendTlvRequest(*message, tlvs, sizeof(tlvs)));
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xfe80);
+    destination.mFields.m16[0] = HostSwap16(0xfe80);
     destination.SetIid(mParent.mMacAddr);
     SuccessOrExit(error = SendMessage(*message, destination));
     otLogInfoMle("Sent Child ID Request\n");
@@ -1099,7 +1099,7 @@ ThreadError Mle::SendChildUpdateRequest(void)
     }
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xfe80);
+    destination.mFields.m16[0] = HostSwap16(0xfe80);
     destination.SetIid(mParent.mMacAddr);
     SuccessOrExit(error = SendMessage(*message, destination));
 
@@ -1945,7 +1945,7 @@ ThreadError Mle::CheckReachability(uint16_t aMeshSource, uint16_t aMeshDest, Ip6
     }
 
     memcpy(&dst, GetMeshLocal16(), kRlocPrefixLength);
-    dst.m16[7] = HostSwap16(aMeshSource);
+    dst.mFields.m16[7] = HostSwap16(aMeshSource);
     Ip6::Icmp::SendError(dst, Ip6::IcmpHeader::kTypeDstUnreach, Ip6::IcmpHeader::kCodeDstUnreachNoRoute, aIp6Header);
 
 exit:
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 1f33fb3be..4a7d8b0a7 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -467,8 +467,8 @@ ThreadError MleRouter::SendAdvertisement(void)
     }
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xff02);
-    destination.m16[7] = HostSwap16(0x0001);
+    destination.mFields.m16[0] = HostSwap16(0xff02);
+    destination.mFields.m16[7] = HostSwap16(0x0001);
     SuccessOrExit(error = SendMessage(*message, destination));
 
     otLogInfoMle("Sent advertisement\n");
@@ -528,9 +528,9 @@ ThreadError MleRouter::SendLinkRequest(Neighbor *aNeighbor)
         }
 
         SuccessOrExit(error = AppendChallenge(*message, mChallenge, sizeof(mChallenge)));
-        destination.m8[0] = 0xff;
-        destination.m8[1] = 0x02;
-        destination.m8[15] = 2;
+        destination.mFields.m8[0] = 0xff;
+        destination.mFields.m8[1] = 0x02;
+        destination.mFields.m8[15] = 2;
     }
     else
     {
@@ -540,7 +540,7 @@ ThreadError MleRouter::SendLinkRequest(Neighbor *aNeighbor)
         }
 
         SuccessOrExit(error = AppendChallenge(*message, mChallenge, sizeof(mChallenge)));
-        destination.m16[0] = HostSwap16(0xfe80);
+        destination.mFields.m16[0] = HostSwap16(0xfe80);
         destination.SetIid(aNeighbor->mMacAddr);
     }
 
@@ -1539,7 +1539,7 @@ ThreadError MleRouter::SendParentResponse(Child *aChild, const ChallengeTlv &cha
     SuccessOrExit(error = AppendVersion(*message));
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xfe80);
+    destination.mFields.m16[0] = HostSwap16(0xfe80);
     destination.SetIid(aChild->mMacAddr);
     SuccessOrExit(error = SendMessage(*message, destination));
 
@@ -1802,8 +1802,8 @@ ThreadError MleRouter::HandleNetworkDataUpdateRouter(void)
     VerifyOrExit(mDeviceState == kDeviceStateRouter || mDeviceState == kDeviceStateLeader, ;);
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xff02);
-    destination.m16[7] = HostSwap16(0x0001);
+    destination.mFields.m16[0] = HostSwap16(0xff02);
+    destination.mFields.m16[7] = HostSwap16(0x0001);
 
     SendDataResponse(destination, tlvs, sizeof(tlvs));
 
@@ -1857,7 +1857,7 @@ ThreadError MleRouter::SendChildIdResponse(Child *aChild)
     mNetif.SetStateChangedFlags(OT_THREAD_CHILD_ADDED);
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xfe80);
+    destination.mFields.m16[0] = HostSwap16(0xfe80);
     destination.SetIid(aChild->mMacAddr);
     SuccessOrExit(error = SendMessage(*message, destination));
 
@@ -2084,12 +2084,12 @@ Neighbor *MleRouter::GetNeighbor(const Ip6::Address &aAddress)
 
     if (aAddress.IsLinkLocal())
     {
-        if (aAddress.m16[4] == HostSwap16(0x0000) &&
-            aAddress.m16[5] == HostSwap16(0x00ff) &&
-            aAddress.m16[6] == HostSwap16(0xfe00))
+        if (aAddress.mFields.m16[4] == HostSwap16(0x0000) &&
+            aAddress.mFields.m16[5] == HostSwap16(0x00ff) &&
+            aAddress.mFields.m16[6] == HostSwap16(0xfe00))
         {
             macaddr.mLength = sizeof(macaddr.mShortAddress);
-            macaddr.mShortAddress = HostSwap16(aAddress.m16[7]);
+            macaddr.mShortAddress = HostSwap16(aAddress.mFields.m16[7]);
         }
         else
         {
@@ -2115,17 +2115,17 @@ Neighbor *MleRouter::GetNeighbor(const Ip6::Address &aAddress)
         }
 
         if (context.mContextId == 0 &&
-            aAddress.m16[4] == HostSwap16(0x0000) &&
-            aAddress.m16[5] == HostSwap16(0x00ff) &&
-            aAddress.m16[6] == HostSwap16(0xfe00) &&
-            aAddress.m16[7] == HostSwap16(child->mValid.mRloc16))
+            aAddress.mFields.m16[4] == HostSwap16(0x0000) &&
+            aAddress.mFields.m16[5] == HostSwap16(0x00ff) &&
+            aAddress.mFields.m16[6] == HostSwap16(0xfe00) &&
+            aAddress.mFields.m16[7] == HostSwap16(child->mValid.mRloc16))
         {
             ExitNow(rval = child);
         }
 
         for (int j = 0; j < Child::kMaxIp6AddressPerChild; j++)
         {
-            if (memcmp(&child->mIp6Address[j], aAddress.m8, sizeof(child->mIp6Address[j])) == 0)
+            if (memcmp(&child->mIp6Address[j], aAddress.mFields.m8, sizeof(child->mIp6Address[j])) == 0)
             {
                 ExitNow(rval = child);
             }
@@ -2143,10 +2143,10 @@ Neighbor *MleRouter::GetNeighbor(const Ip6::Address &aAddress)
             continue;
         }
 
-        if (aAddress.m16[4] == HostSwap16(0x0000) &&
-            aAddress.m16[5] == HostSwap16(0x00ff) &&
-            aAddress.m16[6] == HostSwap16(0xfe00) &&
-            aAddress.m16[7] == HostSwap16(router->mValid.mRloc16))
+        if (aAddress.mFields.m16[4] == HostSwap16(0x0000) &&
+            aAddress.mFields.m16[5] == HostSwap16(0x00ff) &&
+            aAddress.mFields.m16[6] == HostSwap16(0xfe00) &&
+            aAddress.mFields.m16[7] == HostSwap16(router->mValid.mRloc16))
         {
             ExitNow(rval = router);
         }
@@ -2216,7 +2216,7 @@ void MleRouter::HandleMacDataRequest(const Child &aChild)
     VerifyOrExit(aChild.mState == Neighbor::kStateValid && (aChild.mMode & ModeTlv::kModeRxOnWhenIdle) == 0, ;);
 
     memset(&destination, 0, sizeof(destination));
-    destination.m16[0] = HostSwap16(0xfe80);
+    destination.mFields.m16[0] = HostSwap16(0xfe80);
     destination.SetIid(aChild.mMacAddr);
 
     if (aChild.mMode & ModeTlv::kModeFullNetworkData)
@@ -2286,7 +2286,7 @@ ThreadError MleRouter::CheckReachability(uint16_t aMeshSource, uint16_t aMeshDes
     }
 
     memcpy(&destination, GetMeshLocal16(), 14);
-    destination.m16[7] = HostSwap16(aMeshSource);
+    destination.mFields.m16[7] = HostSwap16(aMeshSource);
     Ip6::Icmp::SendError(destination, Ip6::IcmpHeader::kTypeDstUnreach, Ip6::IcmpHeader::kCodeDstUnreachNoRoute,
                          aIp6Header);
 
@@ -2336,7 +2336,7 @@ ThreadError MleRouter::SendAddressSolicit(void)
     messageInfo.mPeerPort = kCoapUdpPort;
     SuccessOrExit(error = mSocket.SendTo(*message, messageInfo));
 
-    otLogInfoMle("Sent address solicit to %04x\n", HostSwap16(messageInfo.GetPeerAddr().m16[7]));
+    otLogInfoMle("Sent address solicit to %04x\n", HostSwap16(messageInfo.GetPeerAddr().mFields.m16[7]));
 
 exit:
     return error;
diff --git a/src/core/thread/network_data_leader.cpp b/src/core/thread/network_data_leader.cpp
index 2383e7c42..a67313b0d 100644
--- a/src/core/thread/network_data_leader.cpp
+++ b/src/core/thread/network_data_leader.cpp
@@ -109,7 +109,7 @@ ThreadError Leader::GetContext(const Ip6::Address &aAddress, Lowpan::Context &aC
 
     aContext.mPrefixLength = 0;
 
-    if (PrefixMatch(mMle.GetMeshLocalPrefix(), aAddress.m8, 64) >= 0)
+    if (PrefixMatch(mMle.GetMeshLocalPrefix(), aAddress.mFields.m8, 64) >= 0)
     {
         aContext.mPrefix = mMle.GetMeshLocalPrefix();
         aContext.mPrefixLength = 64;
@@ -127,7 +127,7 @@ ThreadError Leader::GetContext(const Ip6::Address &aAddress, Lowpan::Context &aC
 
         prefix = reinterpret_cast<PrefixTlv *>(cur);
 
-        if (PrefixMatch(prefix->GetPrefix(), aAddress.m8, prefix->GetPrefixLength()) < 0)
+        if (PrefixMatch(prefix->GetPrefix(), aAddress.mFields.m8, prefix->GetPrefixLength()) < 0)
         {
             continue;
         }
@@ -253,7 +253,7 @@ ThreadError Leader::ConfigureAddress(PrefixTlv &aPrefix)
     {
         if (mAddresses[i].mValidLifetime != 0 &&
             mAddresses[i].mPrefixLength == aPrefix.GetPrefixLength() &&
-            PrefixMatch(mAddresses[i].mAddress.m8, aPrefix.GetPrefix(), aPrefix.GetPrefixLength()) >= 0)
+            PrefixMatch(mAddresses[i].mAddress.mFields.m8, aPrefix.GetPrefix(), aPrefix.GetPrefixLength()) >= 0)
         {
             mAddresses[i].mPreferredLifetime = entry->IsPreferred() ? 0xffffffff : 0;
             ExitNow();
@@ -269,11 +269,11 @@ ThreadError Leader::ConfigureAddress(PrefixTlv &aPrefix)
         }
 
         memset(&mAddresses[i], 0, sizeof(mAddresses[i]));
-        memcpy(mAddresses[i].mAddress.m8, aPrefix.GetPrefix(), BitVectorBytes(aPrefix.GetPrefixLength()));
+        memcpy(mAddresses[i].mAddress.mFields.m8, aPrefix.GetPrefix(), BitVectorBytes(aPrefix.GetPrefixLength()));
 
         for (size_t j = 8; j < sizeof(mAddresses[i].mAddress); j++)
         {
-            mAddresses[i].mAddress.m8[j] = otPlatRandomGet();
+            mAddresses[i].mAddress.mFields.m8[j] = otPlatRandomGet();
         }
 
         mAddresses[i].mPrefixLength = aPrefix.GetPrefixLength();
@@ -292,7 +292,7 @@ bool Leader::IsOnMesh(const Ip6::Address &aAddress)
     PrefixTlv *prefix;
     bool rval = false;
 
-    if (memcmp(aAddress.m8, mMle.GetMeshLocalPrefix(), 8) == 0)
+    if (memcmp(aAddress.mFields.m8, mMle.GetMeshLocalPrefix(), 8) == 0)
     {
         ExitNow(rval = true);
     }
@@ -308,7 +308,7 @@ bool Leader::IsOnMesh(const Ip6::Address &aAddress)
 
         prefix = reinterpret_cast<PrefixTlv *>(cur);
 
-        if (PrefixMatch(prefix->GetPrefix(), aAddress.m8, prefix->GetPrefixLength()) < 0)
+        if (PrefixMatch(prefix->GetPrefix(), aAddress.mFields.m8, prefix->GetPrefixLength()) < 0)
         {
             continue;
         }
@@ -342,7 +342,7 @@ ThreadError Leader::RouteLookup(const Ip6::Address &aSource, const Ip6::Address
 
         prefix = reinterpret_cast<PrefixTlv *>(cur);
 
-        if (PrefixMatch(prefix->GetPrefix(), aSource.m8, prefix->GetPrefixLength()) >= 0)
+        if (PrefixMatch(prefix->GetPrefix(), aSource.mFields.m8, prefix->GetPrefixLength()) >= 0)
         {
             if (ExternalRouteLookup(prefix->GetDomainId(), aDestination, aPrefixMatch, aRloc16) == kThreadError_None)
             {
@@ -393,7 +393,7 @@ ThreadError Leader::ExternalRouteLookup(uint8_t aDomainId, const Ip6::Address &a
             continue;
         }
 
-        plen = PrefixMatch(prefix->GetPrefix(), aDestination.m8, prefix->GetPrefixLength());
+        plen = PrefixMatch(prefix->GetPrefix(), aDestination.mFields.m8, prefix->GetPrefixLength());
 
         if (plen > rval_plen)
         {
@@ -555,7 +555,7 @@ void Leader::HandleServerData(Coap::Header &aHeader, Message &aMessage,
     tlvsLength = aMessage.GetLength() - aMessage.GetOffset();
 
     aMessage.Read(aMessage.GetOffset(), tlvsLength, tlvs);
-    rloc16 = HostSwap16(aMessageInfo.mPeerAddr.m16[7]);
+    rloc16 = HostSwap16(aMessageInfo.mPeerAddr.mFields.m16[7]);
 
     SendServerDataResponse(aHeader, aMessageInfo, tlvs, tlvsLength);
     RegisterNetworkData(rloc16, tlvs, tlvsLength);
diff --git a/src/ncp/Makefile.am b/src/ncp/Makefile.am
index d8e475346..c667f191b 100644
--- a/src/ncp/Makefile.am
+++ b/src/ncp/Makefile.am
@@ -41,6 +41,7 @@ libopenthread_ncp_a_CPPFLAGS        = \
     -I$(top_srcdir)/src               \
     -I$(top_srcdir)/src/core          \
     -I$(top_srcdir)/third_party       \
+    -D_GNU_SOURCE                     \
     $(OPENTHREAD_TARGET_DEFINES)      \
     $(NULL)
 
@@ -71,7 +72,7 @@ if OPENTHREAD_BUILD_TESTS
 
 noinst_PROGRAMS                     = spinel-test
 spinel_test_SOURCES                 = spinel.c
-spinel_test_CFLAGS                  = -DSPINEL_SELF_TEST=1
+spinel_test_CFLAGS                  = -DSPINEL_SELF_TEST=1 -D_GNU_SOURCE
 
 TESTS = spinel-test
 
diff --git a/src/ncp/ncp_base.cpp b/src/ncp/ncp_base.cpp
index 39981b1ec..8600ff53a 100644
--- a/src/ncp/ncp_base.cpp
+++ b/src/ncp/ncp_base.cpp
@@ -1501,10 +1501,10 @@ void NcpBase::GetPropertyHandler_IPV6_ML_PREFIX(uint8_t header, spinel_prop_key_
     {
         otIp6Address addr;
 
-        memcpy(addr.m8, ml_prefix, 8);
+        memcpy(addr.mFields.m8, ml_prefix, 8);
 
         // Zero out the last 8 bytes.
-        memset(addr.m8 + 8, 0, 8);
+        memset(addr.mFields.m8 + 8, 0, 8);
 
         SendPropteryUpdate(
             header,
diff --git a/src/ncp/spinel.c b/src/ncp/spinel.c
index 62369abc6..35a71af6a 100644
--- a/src/ncp/spinel.c
+++ b/src/ncp/spinel.c
@@ -346,7 +346,7 @@ spinel_datatype_vunpack(const uint8_t *data_ptr, spinel_size_t data_len, const c
 
         case SPINEL_DATATYPE_UINT_PACKED_C:
         {
-            uint32_t *arg_ptr = va_arg(args, uint32_t *);
+            unsigned int *arg_ptr = va_arg(args, unsigned int *);
             spinel_ssize_t pui_len = spinel_packed_uint_decode(data_ptr, data_len, arg_ptr);
 
             require(pui_len > 0, bail);