diff --git a/mingw.mutex.h b/mingw.mutex.h
index a5fdecd..869378c 100644
--- a/mingw.mutex.h
+++ b/mingw.mutex.h
@@ -78,6 +78,7 @@ class _NonRecursiveMutex: protected B
 #endif
     }
 protected:
+#ifdef STDTHREAD_STRICT_NONRECURSIVE_LOCKS
     void checkSetOwnerAfterLock()
     {
         DWORD self = GetCurrentThreadId();
@@ -100,6 +101,7 @@ class _NonRecursiveMutex: protected B
         }
         mOwnerThread = 0;
     }
+#endif
 public:
     void unlock()
     {