diff --git a/m-thread.h b/m-thread.h
index 34237641..9af6ab2b 100644
--- a/m-thread.h
+++ b/m-thread.h
@@ -480,7 +480,7 @@ static inline void m_once_call(m_once_t o, void (*func)(void))
   pthread_once(o,func);
 }
 
-#ifdef defined(__GNUC__)
+#if defined(__GNUC__)
 # define M_THREAD_ATTR __thread
 #else
 # define M_THREAD_ATTR  /* Not supported */