diff --git a/simgear/nasal/thread-win32.c b/simgear/nasal/thread-win32.c
index ae63023a..7a459560 100644
--- a/simgear/nasal/thread-win32.c
+++ b/simgear/nasal/thread-win32.c
@@ -13,9 +13,11 @@ void* naNewLock()
 
 void  naLock(void* lock)   { EnterCriticalSection((LPCRITICAL_SECTION)lock); }
 void  naUnlock(void* lock) { LeaveCriticalSection((LPCRITICAL_SECTION)lock); }
+void naFreeLock(void* lock) { free(lock); }
 void* naNewSem()           { return CreateSemaphore(0, 0, MAX_SEM_COUNT, 0); }
 void  naSemDown(void* sem) { WaitForSingleObject((HANDLE)sem, INFINITE); }
 void  naSemUp(void* sem, int count) { ReleaseSemaphore(sem, count, 0); }
+void naFreeSem(void* sem) { ReleaseSemaphore(sem, 1, 0); }
 
 #endif