diff --git a/lib/System/Mutex.cpp b/lib/System/Mutex.cpp
index f55dd3fe26f..d95c25b39ee 100644
--- a/lib/System/Mutex.cpp
+++ b/lib/System/Mutex.cpp
@@ -101,7 +101,7 @@ Mutex::~Mutex()
     pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
     assert(mutex != 0);
     pthread_mutex_destroy(mutex);
-    assert(mutex != 0);
+    free(mutex);
   }
 }