diff --git a/examples/platforms/posix/alarm.c b/examples/platforms/posix/alarm.c
index be69b2b7b..ef2ca61d2 100644
--- a/examples/platforms/posix/alarm.c
+++ b/examples/platforms/posix/alarm.c
@@ -151,7 +151,11 @@ void platformAlarmUpdateTimeout(struct timeval *aTimeout)
             remaining = 1;
         }
 
-        aTimeout->tv_sec  = (time_t)remaining / US_PER_S;
+#ifndef _WIN32
+        aTimeout->tv_sec = (time_t)remaining / US_PER_S;
+#else
+        aTimeout->tv_sec = (long)remaining / US_PER_S;
+#endif
         aTimeout->tv_usec = remaining % US_PER_S;
     }
 }
diff --git a/examples/platforms/posix/platform-posix.h b/examples/platforms/posix/platform-posix.h
index 94d8e8631..2d797d9eb 100644
--- a/examples/platforms/posix/platform-posix.h
+++ b/examples/platforms/posix/platform-posix.h
@@ -49,7 +49,7 @@
 #include <WinSock2.h>
 #include <windows.h>
 #define POLL WSAPoll
-#define ssize_t int
+#define ssize_t long
 #include <time.h>
 #define localtime _localtime32
 // In user mode, define some Linux functions
diff --git a/examples/platforms/posix/radio.c b/examples/platforms/posix/radio.c
index f4a2f3657..78dc9f9fd 100644
--- a/examples/platforms/posix/radio.c
+++ b/examples/platforms/posix/radio.c
@@ -446,7 +446,11 @@ void platformRadioInit(void)
 
 void platformRadioDeinit(void)
 {
+#ifndef _WIN32
     close(sSockFd);
+#else
+    closesocket(sSockFd);
+#endif
 }
 
 bool otPlatRadioIsEnabled(otInstance *aInstance)
@@ -841,7 +845,7 @@ void otPlatRadioEnableSrcMatch(otInstance *aInstance, bool aEnable)
     sSrcMatchEnabled = aEnable;
 }
 
-otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
 
@@ -881,7 +885,7 @@ exit:
     return error;
 }
 
-otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
 
diff --git a/examples/platforms/posix/sim/radio-sim.c b/examples/platforms/posix/sim/radio-sim.c
index 0279de4fa..d22b9db51 100644
--- a/examples/platforms/posix/sim/radio-sim.c
+++ b/examples/platforms/posix/sim/radio-sim.c
@@ -671,7 +671,7 @@ void otPlatRadioEnableSrcMatch(otInstance *aInstance, bool aEnable)
     sSrcMatchEnabled = aEnable;
 }
 
-otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
 
@@ -711,7 +711,7 @@ exit:
     return error;
 }
 
-otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
 
diff --git a/src/ncp/spinel_decoder.cpp b/src/ncp/spinel_decoder.cpp
index 060a3ac15..5535e687e 100644
--- a/src/ncp/spinel_decoder.cpp
+++ b/src/ncp/spinel_decoder.cpp
@@ -216,7 +216,7 @@ exit:
 }
 
 // Reads an item of given size and updates the pointer `aPtr`.
-otError SpinelDecoder::ReadItem(const uint8_t **aPtr, size_t aSize)
+otError SpinelDecoder::ReadItem(const uint8_t **aPtr, uint16_t aSize)
 {
     otError error = OT_ERROR_NONE;
 
@@ -303,7 +303,8 @@ otError SpinelDecoder::ReadUtf8(const char *&aUtf8)
 
     aUtf8 = reinterpret_cast<const char *>(&mFrame[mIndex]);
 
-    mIndex += (len + sizeof(uint8_t)); // `sizeof(uint8_t)` is added for the terminating null character.
+    // `sizeof(uint8_t)` is added for the terminating null character.
+    mIndex += static_cast<uint16_t>(len + sizeof(uint8_t));
 
 exit:
     return error;
diff --git a/src/ncp/spinel_decoder.hpp b/src/ncp/spinel_decoder.hpp
index 96780cdd5..1fee147ab 100644
--- a/src/ncp/spinel_decoder.hpp
+++ b/src/ncp/spinel_decoder.hpp
@@ -564,7 +564,7 @@ public:
     otError ResetToSaved(void);
 
 private:
-    otError ReadItem(const uint8_t **aPtr, size_t aSize);
+    otError ReadItem(const uint8_t **aPtr, uint16_t aSize);
     void    ClearSavedPosition(void) { mSavedIndex = mLength; }
     bool    IsSavedPositionValid(void) const { return (mSavedIndex < mLength); }
 
diff --git a/src/posix/platform/radio_spinel.cpp b/src/posix/platform/radio_spinel.cpp
index 1aacfd8da..989dc05ee 100644
--- a/src/posix/platform/radio_spinel.cpp
+++ b/src/posix/platform/radio_spinel.cpp
@@ -1467,7 +1467,7 @@ void otPlatRadioEnableSrcMatch(otInstance *aInstance, bool aEnable)
     OT_UNUSED_VARIABLE(aInstance);
 }
 
-otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioAddSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
     return sRadioSpinel.AddSrcMatchShortEntry(aShortAddress);
@@ -1486,7 +1486,7 @@ otError otPlatRadioAddSrcMatchExtEntry(otInstance *aInstance, const otExtAddress
     return sRadioSpinel.AddSrcMatchExtEntry(addr);
 }
 
-otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, const uint16_t aShortAddress)
+otError otPlatRadioClearSrcMatchShortEntry(otInstance *aInstance, uint16_t aShortAddress)
 {
     OT_UNUSED_VARIABLE(aInstance);
     return sRadioSpinel.ClearSrcMatchShortEntry(aShortAddress);
diff --git a/tests/unit/test_link_quality.cpp b/tests/unit/test_link_quality.cpp
index caccb117c..262847b79 100644
--- a/tests/unit/test_link_quality.cpp
+++ b/tests/unit/test_link_quality.cpp
@@ -142,7 +142,7 @@ int8_t GetRandomRss(void)
     uint32_t value;
 
     value = otPlatRandomGet() % 128;
-    return static_cast<int8_t>(-value);
+    return -static_cast<int8_t>(value);
 }
 
 void TestRssAveraging(void)