diff --git a/channels/urbdrc/client/libusb/libusb_udevman.c b/channels/urbdrc/client/libusb/libusb_udevman.c
index 27f9644db..541d0e366 100644
--- a/channels/urbdrc/client/libusb/libusb_udevman.c
+++ b/channels/urbdrc/client/libusb/libusb_udevman.c
@@ -442,7 +442,7 @@ static void udevman_loading_lock(IUDEVMAN* idevman)
 static void udevman_loading_unlock(IUDEVMAN* idevman)
 {
 	UDEVMAN* udevman = (UDEVMAN*)idevman;
-	ReleaseMutex(udevman->devman_loading);
+	(void)ReleaseMutex(udevman->devman_loading);
 }
 
 BASIC_STATE_FUNC_DEFINED(device_num, UINT32)
diff --git a/client/X11/xf_client.c b/client/X11/xf_client.c
index cb599e0f4..d02134830 100644
--- a/client/X11/xf_client.c
+++ b/client/X11/xf_client.c
@@ -827,7 +827,7 @@ void xf_unlock_x11_(xfContext* xfc, const char* fkt)
 #endif
 
 	if (!xfc->UseXThreads)
-		ReleaseMutex(xfc->mutex);
+		(void)ReleaseMutex(xfc->mutex);
 	else
 		XUnlockDisplay(xfc->display);
 }
diff --git a/winpr/libwinpr/interlocked/interlocked.c b/winpr/libwinpr/interlocked/interlocked.c
index b560f5947..c9a83de16 100644
--- a/winpr/libwinpr/interlocked/interlocked.c
+++ b/winpr/libwinpr/interlocked/interlocked.c
@@ -330,7 +330,7 @@ LONGLONG InterlockedCompareExchange64(LONGLONG volatile* Destination, LONGLONG E
 		*Destination = Exchange;
 
 	if (locked)
-		ReleaseMutex(mutex);
+		(void)ReleaseMutex(mutex);
 	else
 		(void)fprintf(stderr,
 		              "WARNING: InterlockedCompareExchange64 operation might have failed\n");
diff --git a/winpr/libwinpr/synch/test/TestSynchMutex.c b/winpr/libwinpr/synch/test/TestSynchMutex.c
index 0d4d05126..4744f054a 100644
--- a/winpr/libwinpr/synch/test/TestSynchMutex.c
+++ b/winpr/libwinpr/synch/test/TestSynchMutex.c
@@ -229,8 +229,8 @@ static BOOL test_mutex_threading(void)
 	CloseHandle(thread1_mutex2);
 	return TRUE;
 fail:
-	ReleaseMutex(thread1_mutex1);
-	ReleaseMutex(thread1_mutex2);
+	(void)ReleaseMutex(thread1_mutex1);
+	(void)ReleaseMutex(thread1_mutex2);
 	CloseHandle(thread1_mutex1);
 	CloseHandle(thread1_mutex2);
 	CloseHandle(hStartEvent);
diff --git a/winpr/libwinpr/utils/ssl.c b/winpr/libwinpr/utils/ssl.c
index 2f85206ed..08002dc1b 100644
--- a/winpr/libwinpr/utils/ssl.c
+++ b/winpr/libwinpr/utils/ssl.c
@@ -79,7 +79,7 @@ static void _winpr_openssl_locking(int mode, int type, const char* file, int lin
 	}
 	else
 	{
-		ReleaseMutex(g_winpr_openssl_locks[type]);
+		(void)ReleaseMutex(g_winpr_openssl_locks[type]);
 	}
 }
 
@@ -108,7 +108,7 @@ static void _winpr_openssl_dynlock_lock(int mode, struct CRYPTO_dynlock_value* d
 	}
 	else
 	{
-		ReleaseMutex(dynlock->mutex);
+		(void)ReleaseMutex(dynlock->mutex);
 	}
 }