diff --git a/lib/common/threading.h b/lib/common/threading.h
index ee7864555..99e39b551 100644
--- a/lib/common/threading.h
+++ b/lib/common/threading.h
@@ -42,14 +42,14 @@ extern "C" {
 
 /* mutex */
 #define pthread_mutex_t           CRITICAL_SECTION
-#define pthread_mutex_init(a,b)   (InitializeCriticalSection((a)), 0)
+#define pthread_mutex_init(a,b)   (InitializeCriticalSection((a)), (void)0)
 #define pthread_mutex_destroy(a)  DeleteCriticalSection((a))
 #define pthread_mutex_lock(a)     EnterCriticalSection((a))
 #define pthread_mutex_unlock(a)   LeaveCriticalSection((a))
 
 /* condition variable */
 #define pthread_cond_t             CONDITION_VARIABLE
-#define pthread_cond_init(a, b)    (InitializeConditionVariable((a)), 0)
+#define pthread_cond_init(a, b)    (InitializeConditionVariable((a)), (void)0)
 #define pthread_cond_destroy(a)    /* No delete */
 #define pthread_cond_wait(a, b)    SleepConditionVariableCS((a), (b), INFINITE)
 #define pthread_cond_signal(a)     WakeConditionVariable((a))