diff --git a/examples/drivers/windows/otApi/otApi.cpp b/examples/drivers/windows/otApi/otApi.cpp
index 86b4d66d0..b30c06074 100644
--- a/examples/drivers/windows/otApi/otApi.cpp
+++ b/examples/drivers/windows/otApi/otApi.cpp
@@ -1671,7 +1671,7 @@ otThreadGetMeshLocalEid(
 }
 
 OTAPI
-const uint8_t *
+const otMeshLocalPrefix *
 OTCALL
 otThreadGetMeshLocalPrefix(
     _In_ otInstance *aInstance
@@ -1685,7 +1685,7 @@ otThreadGetMeshLocalPrefix(
         free(Result);
         Result = nullptr;
     }
-    return (uint8_t*)Result;
+    return Result;
 }
 
 OTAPI
@@ -1693,11 +1693,11 @@ otError
 OTCALL
 otThreadSetMeshLocalPrefix(
     _In_ otInstance *aInstance, 
-    const uint8_t *aMeshLocalPrefix
+    const otMeshLocalPrefix *aMeshLocalPrefix
     )
 {
     if (aInstance == nullptr) return OT_ERROR_INVALID_ARGS;
-    return DwordToThreadError(SetIOCTL(aInstance, IOCTL_OTLWF_OT_MESH_LOCAL_PREFIX, (const otMeshLocalPrefix*)aMeshLocalPrefix));
+    return DwordToThreadError(SetIOCTL(aInstance, IOCTL_OTLWF_OT_MESH_LOCAL_PREFIX, aMeshLocalPrefix));
 }
 
 OTAPI
diff --git a/examples/drivers/windows/otLwf/iocontrol.c b/examples/drivers/windows/otLwf/iocontrol.c
index aff992478..b3553aff4 100644
--- a/examples/drivers/windows/otLwf/iocontrol.c
+++ b/examples/drivers/windows/otLwf/iocontrol.c
@@ -1936,12 +1936,13 @@ otLwfIoCtl_otMeshLocalPrefix(
 
     if (InBufferLength >= sizeof(otMeshLocalPrefix))
     {
-        status = ThreadErrorToNtstatus(otThreadSetMeshLocalPrefix(pFilter->otCtx, InBuffer));
+        status = ThreadErrorToNtstatus(otThreadSetMeshLocalPrefix(pFilter->otCtx, (otMeshLocalPrefix*)InBuffer));
         *OutBufferLength = 0;
     }
     else if (*OutBufferLength >= sizeof(otMeshLocalPrefix))
     {
-        memcpy(OutBuffer, otThreadGetMeshLocalPrefix(pFilter->otCtx), sizeof(otMeshLocalPrefix));
+        const otMeshLocalPrefix* aMeshLocalPrefix = otThreadGetMeshLocalPrefix(pFilter->otCtx);
+        memcpy(OutBuffer, aMeshLocalPrefix, sizeof(otMeshLocalPrefix));
         *OutBufferLength = sizeof(otMeshLocalPrefix);
         status = STATUS_SUCCESS;
     }
diff --git a/include/openthread/dataset.h b/include/openthread/dataset.h
index 656919530..a88f487b1 100644
--- a/include/openthread/dataset.h
+++ b/include/openthread/dataset.h
@@ -104,10 +104,17 @@ typedef struct otExtendedPanId otExtendedPanId;
  * This structure represents a Mesh Local Prefix.
  *
  */
-typedef struct otMeshLocalPrefix
+OT_TOOL_PACKED_BEGIN
+struct otMeshLocalPrefix
 {
     uint8_t m8[OT_MESH_LOCAL_PREFIX_SIZE]; ///< Byte values
-} otMeshLocalPrefix;
+} OT_TOOL_PACKED_END;
+
+/**
+ * This structure represents a Mesh Local Prefix
+ *
+ */
+typedef struct otMeshLocalPrefix otMeshLocalPrefix;
 
 #define OT_PSKC_MAX_SIZE 16 ///< Maximum size of the PSKc (bytes)
 
diff --git a/include/openthread/thread.h b/include/openthread/thread.h
index 0d4dd0a39..9c2bbae71 100644
--- a/include/openthread/thread.h
+++ b/include/openthread/thread.h
@@ -364,7 +364,7 @@ OTAPI const otIp6Address *OTCALL otThreadGetMeshLocalEid(otInstance *aInstance);
  * @returns A pointer to the Mesh Local Prefix.
  *
  */
-OTAPI const uint8_t *OTCALL otThreadGetMeshLocalPrefix(otInstance *aInstance);
+OTAPI const otMeshLocalPrefix *OTCALL otThreadGetMeshLocalPrefix(otInstance *aInstance);
 
 /**
  * This function sets the Mesh Local Prefix.
@@ -380,7 +380,7 @@ OTAPI const uint8_t *OTCALL otThreadGetMeshLocalPrefix(otInstance *aInstance);
  * @retval OT_ERROR_INVALID_STATE  Thread protocols are enabled.
  *
  */
-OTAPI otError OTCALL otThreadSetMeshLocalPrefix(otInstance *aInstance, const uint8_t *aMeshLocalPrefix);
+OTAPI otError OTCALL otThreadSetMeshLocalPrefix(otInstance *aInstance, const otMeshLocalPrefix *aMeshLocalPrefix);
 
 /**
  * This function returns the Thread link-local IPv6 address.
diff --git a/src/core/api/thread_api.cpp b/src/core/api/thread_api.cpp
index a9ff568af..d76612721 100644
--- a/src/core/api/thread_api.cpp
+++ b/src/core/api/thread_api.cpp
@@ -66,20 +66,20 @@ const otExtendedPanId *otThreadGetExtendedPanId(otInstance *aInstance)
 
 otError otThreadSetExtendedPanId(otInstance *aInstance, const otExtendedPanId *aExtendedPanId)
 {
-    otError   error    = OT_ERROR_NONE;
-    Instance &instance = *static_cast<Instance *>(aInstance);
-    uint8_t   mlPrefix[8];
+    otError           error    = OT_ERROR_NONE;
+    Instance &        instance = *static_cast<Instance *>(aInstance);
+    otMeshLocalPrefix prefix;
 
     VerifyOrExit(instance.GetThreadNetif().GetMle().GetRole() == OT_DEVICE_ROLE_DISABLED,
                  error = OT_ERROR_INVALID_STATE);
 
     instance.GetThreadNetif().GetMac().SetExtendedPanId(*aExtendedPanId);
 
-    mlPrefix[0] = 0xfd;
-    memcpy(mlPrefix + 1, aExtendedPanId->m8, 5);
-    mlPrefix[6] = 0x00;
-    mlPrefix[7] = 0x00;
-    instance.GetThreadNetif().GetMle().SetMeshLocalPrefix(mlPrefix);
+    prefix.m8[0] = 0xfd;
+    memcpy(&prefix.m8[1], aExtendedPanId->m8, 5);
+    prefix.m8[6] = 0x00;
+    prefix.m8[7] = 0x00;
+    instance.GetThreadNetif().GetMle().SetMeshLocalPrefix(prefix);
 
     instance.GetThreadNetif().GetActiveDataset().Clear();
     instance.GetThreadNetif().GetPendingDataset().Clear();
@@ -191,14 +191,14 @@ const otIp6Address *otThreadGetMeshLocalEid(otInstance *aInstance)
     return &instance.GetThreadNetif().GetMle().GetMeshLocal64();
 }
 
-const uint8_t *otThreadGetMeshLocalPrefix(otInstance *aInstance)
+const otMeshLocalPrefix *otThreadGetMeshLocalPrefix(otInstance *aInstance)
 {
     Instance &instance = *static_cast<Instance *>(aInstance);
 
-    return instance.GetThreadNetif().GetMle().GetMeshLocalPrefix();
+    return &instance.GetThreadNetif().GetMle().GetMeshLocalPrefix();
 }
 
-otError otThreadSetMeshLocalPrefix(otInstance *aInstance, const uint8_t *aMeshLocalPrefix)
+otError otThreadSetMeshLocalPrefix(otInstance *aInstance, const otMeshLocalPrefix *aMeshLocalPrefix)
 {
     otError   error    = OT_ERROR_NONE;
     Instance &instance = *static_cast<Instance *>(aInstance);
@@ -206,7 +206,7 @@ otError otThreadSetMeshLocalPrefix(otInstance *aInstance, const uint8_t *aMeshLo
     VerifyOrExit(instance.GetThreadNetif().GetMle().GetRole() == OT_DEVICE_ROLE_DISABLED,
                  error = OT_ERROR_INVALID_STATE);
 
-    error = instance.GetThreadNetif().GetMle().SetMeshLocalPrefix(aMeshLocalPrefix);
+    error = instance.GetThreadNetif().GetMle().SetMeshLocalPrefix(*aMeshLocalPrefix);
     instance.GetThreadNetif().GetActiveDataset().Clear();
     instance.GetThreadNetif().GetPendingDataset().Clear();
 
diff --git a/src/core/meshcop/dataset.cpp b/src/core/meshcop/dataset.cpp
index 30f02f8f0..f672ae30f 100644
--- a/src/core/meshcop/dataset.cpp
+++ b/src/core/meshcop/dataset.cpp
@@ -174,8 +174,8 @@ void Dataset::Get(otOperationalDataset &aDataset) const
 
         case Tlv::kMeshLocalPrefix:
         {
-            const MeshLocalPrefixTlv *tlv = static_cast<const MeshLocalPrefixTlv *>(cur);
-            memcpy(aDataset.mMeshLocalPrefix.m8, tlv->GetMeshLocalPrefix(), sizeof(aDataset.mMeshLocalPrefix));
+            const MeshLocalPrefixTlv *tlv                  = static_cast<const MeshLocalPrefixTlv *>(cur);
+            aDataset.mMeshLocalPrefix                      = tlv->GetMeshLocalPrefix();
             aDataset.mComponents.mIsMeshLocalPrefixPresent = true;
             break;
         }
@@ -318,7 +318,7 @@ otError Dataset::Set(const otOperationalDataset &aDataset)
     {
         MeshCoP::MeshLocalPrefixTlv tlv;
         tlv.Init();
-        tlv.SetMeshLocalPrefix(aDataset.mMeshLocalPrefix.m8);
+        tlv.SetMeshLocalPrefix(aDataset.mMeshLocalPrefix);
         Set(tlv);
     }
 
diff --git a/src/core/meshcop/dataset_manager_ftd.cpp b/src/core/meshcop/dataset_manager_ftd.cpp
index 3369b989a..11ea3fc8b 100644
--- a/src/core/meshcop/dataset_manager_ftd.cpp
+++ b/src/core/meshcop/dataset_manager_ftd.cpp
@@ -178,7 +178,8 @@ otError DatasetManager::Set(Coap::Header &aHeader, Message &aMessage, const Ip6:
     // check mesh local prefix
     if (Tlv::GetTlv(aMessage, Tlv::kMeshLocalPrefix, sizeof(meshLocalPrefix), meshLocalPrefix) == OT_ERROR_NONE &&
         meshLocalPrefix.IsValid() &&
-        memcmp(meshLocalPrefix.GetMeshLocalPrefix(), netif.GetMle().GetMeshLocalPrefix(), meshLocalPrefix.GetLength()))
+        memcmp(&meshLocalPrefix.GetMeshLocalPrefix(), &netif.GetMle().GetMeshLocalPrefix(),
+               meshLocalPrefix.GetLength()))
     {
         doesAffectConnectivity = true;
     }
@@ -429,7 +430,7 @@ otError DatasetManager::SendSetRequest(const otOperationalDataset &aDataset, con
     {
         MeshLocalPrefixTlv localprefix;
         localprefix.Init();
-        localprefix.SetMeshLocalPrefix(aDataset.mMeshLocalPrefix.m8);
+        localprefix.SetMeshLocalPrefix(aDataset.mMeshLocalPrefix);
         SuccessOrExit(error = message->Append(&localprefix, sizeof(localprefix)));
     }
 
diff --git a/src/core/meshcop/meshcop_tlvs.hpp b/src/core/meshcop/meshcop_tlvs.hpp
index f6c97e830..32432125c 100644
--- a/src/core/meshcop/meshcop_tlvs.hpp
+++ b/src/core/meshcop/meshcop_tlvs.hpp
@@ -591,7 +591,7 @@ public:
      * @returns The Mesh Local Prefix value.
      *
      */
-    const uint8_t *GetMeshLocalPrefix(void) const { return mMeshLocalPrefix; }
+    const otMeshLocalPrefix &GetMeshLocalPrefix(void) const { return mMeshLocalPrefix; }
 
     /**
      * This method sets the Mesh Local Prefix value.
@@ -599,13 +599,10 @@ public:
      * @param[in]  aMeshLocalPrefix  A pointer to the Mesh Local Prefix value.
      *
      */
-    void SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
-    {
-        memcpy(mMeshLocalPrefix, aMeshLocalPrefix, sizeof(mMeshLocalPrefix));
-    }
+    void SetMeshLocalPrefix(const otMeshLocalPrefix &aMeshLocalPrefix) { mMeshLocalPrefix = aMeshLocalPrefix; }
 
 private:
-    uint8_t mMeshLocalPrefix[8];
+    otMeshLocalPrefix mMeshLocalPrefix;
 } OT_TOOL_PACKED_END;
 
 /**
diff --git a/src/core/net/dhcp6_client.cpp b/src/core/net/dhcp6_client.cpp
index 80ab906f6..3fb97694d 100644
--- a/src/core/net/dhcp6_client.cpp
+++ b/src/core/net/dhcp6_client.cpp
@@ -385,7 +385,7 @@ otError Dhcp6Client::Solicit(uint16_t aRloc16)
     SuccessOrExit(error = AppendIaAddress(*message, aRloc16));
     SuccessOrExit(error = AppendRapidCommit(*message));
 
-    memcpy(messageInfo.GetPeerAddr().mFields.m8, netif.GetMle().GetMeshLocalPrefix(), 8);
+    memcpy(messageInfo.GetPeerAddr().mFields.m8, netif.GetMle().GetMeshLocalPrefix().m8, sizeof(otMeshLocalPrefix));
     messageInfo.GetPeerAddr().mFields.m16[4] = HostSwap16(0x0000);
     messageInfo.GetPeerAddr().mFields.m16[5] = HostSwap16(0x00ff);
     messageInfo.GetPeerAddr().mFields.m16[6] = HostSwap16(0xfe00);
diff --git a/src/core/net/dhcp6_server.cpp b/src/core/net/dhcp6_server.cpp
index d6200faae..09549802b 100644
--- a/src/core/net/dhcp6_server.cpp
+++ b/src/core/net/dhcp6_server.cpp
@@ -153,7 +153,7 @@ otError Dhcp6Server::UpdateService(void)
             if (!mAgentsAloc[i].mValid)
             {
                 address = &(mAgentsAloc[i].GetAddress());
-                memcpy(address, netif.GetMle().GetMeshLocalPrefix(), 8);
+                memcpy(address, netif.GetMle().GetMeshLocalPrefix().m8, sizeof(otMeshLocalPrefix));
                 address->mFields.m16[4]      = HostSwap16(0x0000);
                 address->mFields.m16[5]      = HostSwap16(0x00ff);
                 address->mFields.m16[6]      = HostSwap16(0xfe00);
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 1788c0f95..f9cc9db4d 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -110,7 +110,7 @@ Mle::Mle(Instance &aInstance)
     , mAlternateTimestamp(0)
     , mNotifierCallback(&Mle::HandleStateChanged, this)
 {
-    uint8_t meshLocalPrefix[8];
+    otMeshLocalPrefix meshLocalPrefix;
 
     memset(&mLeaderData, 0, sizeof(mLeaderData));
     memset(&mParentLeaderData, 0, sizeof(mParentLeaderData));
@@ -157,10 +157,10 @@ Mle::Mle(Instance &aInstance)
 #endif
 
     // initialize Mesh Local Prefix
-    meshLocalPrefix[0] = 0xfd;
-    memcpy(meshLocalPrefix + 1, GetNetif().GetMac().GetExtendedPanId().m8, 5);
-    meshLocalPrefix[6] = 0x00;
-    meshLocalPrefix[7] = 0x00;
+    meshLocalPrefix.m8[0] = 0xfd;
+    memcpy(&meshLocalPrefix.m8[1], GetNetif().GetMac().GetExtendedPanId().m8, 5);
+    meshLocalPrefix.m8[6] = 0x00;
+    meshLocalPrefix.m8[7] = 0x00;
 
     // mesh-local 64
     Random::FillBuffer(mMeshLocal64.GetAddress().mFields.m8 + OT_IP6_PREFIX_SIZE,
@@ -830,16 +830,16 @@ otError Mle::UpdateLinkLocalAddress(void)
     return OT_ERROR_NONE;
 }
 
-const uint8_t *Mle::GetMeshLocalPrefix(void) const
+const otMeshLocalPrefix &Mle::GetMeshLocalPrefix(void) const
 {
-    return mMeshLocal16.GetAddress().mFields.m8;
+    return reinterpret_cast<const otMeshLocalPrefix &>(mMeshLocal16.GetAddress());
 }
 
-otError Mle::SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
+otError Mle::SetMeshLocalPrefix(const otMeshLocalPrefix &aMeshLocalPrefix)
 {
     ThreadNetif &netif = GetNetif();
 
-    if (memcmp(mMeshLocal64.GetAddress().mFields.m8, aMeshLocalPrefix, 8) == 0)
+    if (memcmp(mMeshLocal64.GetAddress().mFields.m8, aMeshLocalPrefix.m8, sizeof(aMeshLocalPrefix)) == 0)
     {
         GetNotifier().SignalIfFirst(OT_CHANGED_THREAD_ML_ADDR);
         ExitNow();
@@ -851,7 +851,7 @@ otError Mle::SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
     netif.UnsubscribeMulticast(mLinkLocalAllThreadNodes);
     netif.UnsubscribeMulticast(mRealmLocalAllThreadNodes);
 
-    memcpy(mMeshLocal64.GetAddress().mFields.m8, aMeshLocalPrefix, 8);
+    memcpy(mMeshLocal64.GetAddress().mFields.m8, aMeshLocalPrefix.m8, sizeof(aMeshLocalPrefix));
     memcpy(mMeshLocal16.GetAddress().mFields.m8, mMeshLocal64.GetAddress().mFields.m8, 8);
 
 #if OPENTHREAD_ENABLE_SERVICE
diff --git a/src/core/thread/mle.hpp b/src/core/thread/mle.hpp
index 12339aadc..f05a543c5 100644
--- a/src/core/thread/mle.hpp
+++ b/src/core/thread/mle.hpp
@@ -691,20 +691,20 @@ public:
     /**
      * This method returns a pointer to the Mesh Local Prefix.
      *
-     * @returns A pointer to the Mesh Local Prefix.
+     * @returns A reference to the Mesh Local Prefix.
      *
      */
-    const uint8_t *GetMeshLocalPrefix(void) const;
+    const otMeshLocalPrefix &GetMeshLocalPrefix(void) const;
 
     /**
      * This method sets the Mesh Local Prefix.
      *
-     * @param[in]  aPrefix  A pointer to the Mesh Local Prefix.
+     * @param[in]  aPrefix  A reference to the Mesh Local Prefix.
      *
      * @retval OT_ERROR_NONE  Successfully set the Mesh Local Prefix.
      *
      */
-    otError SetMeshLocalPrefix(const uint8_t *aPrefix);
+    otError SetMeshLocalPrefix(const otMeshLocalPrefix &aPrefix);
 
     /**
      * This method returns a reference to the Thread link-local address.
diff --git a/src/core/thread/network_data_leader.cpp b/src/core/thread/network_data_leader.cpp
index 5a1f26b76..559b21bde 100644
--- a/src/core/thread/network_data_leader.cpp
+++ b/src/core/thread/network_data_leader.cpp
@@ -79,9 +79,9 @@ otError LeaderBase::GetContext(const Ip6::Address &aAddress, Lowpan::Context &aC
 
     aContext.mPrefixLength = 0;
 
-    if (PrefixMatch(netif.GetMle().GetMeshLocalPrefix(), aAddress.mFields.m8, 64) >= 0)
+    if (PrefixMatch(netif.GetMle().GetMeshLocalPrefix().m8, aAddress.mFields.m8, 64) >= 0)
     {
-        aContext.mPrefix       = netif.GetMle().GetMeshLocalPrefix();
+        aContext.mPrefix       = netif.GetMle().GetMeshLocalPrefix().m8;
         aContext.mPrefixLength = 64;
         aContext.mContextId    = 0;
         aContext.mCompressFlag = true;
@@ -129,7 +129,7 @@ otError LeaderBase::GetContext(uint8_t aContextId, Lowpan::Context &aContext)
 
     if (aContextId == 0)
     {
-        aContext.mPrefix       = GetNetif().GetMle().GetMeshLocalPrefix();
+        aContext.mPrefix       = GetNetif().GetMle().GetMeshLocalPrefix().m8;
         aContext.mPrefixLength = 64;
         aContext.mContextId    = 0;
         aContext.mCompressFlag = true;
@@ -200,7 +200,7 @@ bool LeaderBase::IsOnMesh(const Ip6::Address &aAddress)
     PrefixTlv *prefix;
     bool       rval = false;
 
-    if (memcmp(aAddress.mFields.m8, GetNetif().GetMle().GetMeshLocalPrefix(), 8) == 0)
+    if (memcmp(aAddress.mFields.m8, GetNetif().GetMle().GetMeshLocalPrefix().m8, sizeof(otMeshLocalPrefix)) == 0)
     {
         ExitNow(rval = true);
     }
diff --git a/src/core/thread/network_data_local.cpp b/src/core/thread/network_data_local.cpp
index 26edd100b..d6938de37 100644
--- a/src/core/thread/network_data_local.cpp
+++ b/src/core/thread/network_data_local.cpp
@@ -57,8 +57,8 @@ otError Local::AddOnMeshPrefix(const uint8_t *aPrefix, uint8_t aPrefixLength, in
     PrefixTlv *      prefixTlv;
     BorderRouterTlv *brTlv;
 
-    VerifyOrExit(Ip6::Address::PrefixMatch(aPrefix, GetNetif().GetMle().GetMeshLocalPrefix(), (aPrefixLength + 7) / 8) <
-                     Ip6::Address::kMeshLocalPrefixLength,
+    VerifyOrExit(Ip6::Address::PrefixMatch(aPrefix, GetNetif().GetMle().GetMeshLocalPrefix().m8,
+                                           (aPrefixLength + 7) / 8) < Ip6::Address::kMeshLocalPrefixLength,
                  error = OT_ERROR_INVALID_ARGS);
 
     RemoveOnMeshPrefix(aPrefix, aPrefixLength);
diff --git a/src/core/thread/topology.cpp b/src/core/thread/topology.cpp
index b4417f41d..53207a737 100644
--- a/src/core/thread/topology.cpp
+++ b/src/core/thread/topology.cpp
@@ -104,7 +104,7 @@ otError Child::GetMeshLocalIp6Address(Instance &aInstance, Ip6::Address &aAddres
 
     VerifyOrExit(!IsAllZero(mMeshLocalIid, sizeof(mMeshLocalIid)), error = OT_ERROR_NOT_FOUND);
 
-    memcpy(aAddress.mFields.m8, aInstance.GetThreadNetif().GetMle().GetMeshLocalPrefix(),
+    memcpy(aAddress.mFields.m8, aInstance.GetThreadNetif().GetMle().GetMeshLocalPrefix().m8,
            Ip6::Address::kMeshLocalPrefixSize);
 
     aAddress.SetIid(mMeshLocalIid);
diff --git a/src/ncp/ncp_base_mtd.cpp b/src/ncp/ncp_base_mtd.cpp
index a13e31676..50c4f587a 100644
--- a/src/ncp/ncp_base_mtd.cpp
+++ b/src/ncp/ncp_base_mtd.cpp
@@ -1046,13 +1046,13 @@ exit:
 
 template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_IPV6_ML_PREFIX>(void)
 {
-    otError        error    = OT_ERROR_NONE;
-    const uint8_t *mlPrefix = otThreadGetMeshLocalPrefix(mInstance);
-    otIp6Address   addr;
+    otError                  error    = OT_ERROR_NONE;
+    const otMeshLocalPrefix *mlPrefix = otThreadGetMeshLocalPrefix(mInstance);
+    otIp6Address             addr;
 
     VerifyOrExit(mlPrefix != NULL); // If `mlPrefix` is NULL send empty response.
 
-    memcpy(addr.mFields.m8, mlPrefix, 8);
+    memcpy(addr.mFields.m8, mlPrefix->m8, 8);
 
     // Zero out the last 8 bytes.
     memset(addr.mFields.m8 + 8, 0, 8);
@@ -1066,15 +1066,15 @@ exit:
 
 template <> otError NcpBase::HandlePropertySet<SPINEL_PROP_IPV6_ML_PREFIX>(void)
 {
-    otError        error = OT_ERROR_NONE;
-    const uint8_t *meshLocalPrefix;
-    uint8_t        prefixLength;
+    otError             error = OT_ERROR_NONE;
+    const otIp6Address *meshLocalPrefix;
+    uint8_t             prefixLength;
 
     SuccessOrExit(error = mDecoder.ReadIp6Address(meshLocalPrefix));
     SuccessOrExit(error = mDecoder.ReadUint8(prefixLength));
     VerifyOrExit(prefixLength == 64, error = OT_ERROR_INVALID_ARGS);
 
-    error = otThreadSetMeshLocalPrefix(mInstance, meshLocalPrefix);
+    error = otThreadSetMeshLocalPrefix(mInstance, reinterpret_cast<const otMeshLocalPrefix *>(meshLocalPrefix));
 
 exit:
     return error;
diff --git a/tests/unit/test_lowpan.cpp b/tests/unit/test_lowpan.cpp
index daba82e09..6ef4437d1 100644
--- a/tests/unit/test_lowpan.cpp
+++ b/tests/unit/test_lowpan.cpp
@@ -109,7 +109,7 @@ void TestIphcVector::GetUncompressedStream(Message &aMessage)
  */
 static void Init()
 {
-    uint8_t meshLocalPrefix[] = {0xfd, 0x00, 0xca, 0xfe, 0xfa, 0xce, 0x12, 0x34};
+    otMeshLocalPrefix meshLocalPrefix = {{0xfd, 0x00, 0xca, 0xfe, 0xfa, 0xce, 0x12, 0x34}};
     sThreadNetif->GetMle().SetMeshLocalPrefix(meshLocalPrefix);
 
     // Emulate global prefixes with contextes.