diff --git a/src/core/debug.h b/src/core/debug.h
index c7025a8b3..34b85e6e4 100644
--- a/src/core/debug.h
+++ b/src/core/debug.h
@@ -118,7 +118,7 @@ private:
  * Generate debugging output unconditionally in all
  * debug builds.
  */
-#define NS_DEBUG_UNCOND (msg) \
+#define NS_DEBUG_UNCOND(msg) \
     std::cout << msg << std::endl;
 
 #else /* NS3_DEBUG_ENABLE */