diff --git a/glx/glxdri2.c b/glx/glxdri2.c
index 69fd39b3b..0f998de75 100644
--- a/glx/glxdri2.c
+++ b/glx/glxdri2.c
@@ -174,7 +174,7 @@ __glXdriSwapEvent(ClientPtr client, void *data, int type, CARD64 ust,
     __GLXdrawable *drawable = data;
     xGLXBufferSwapComplete wire;
 
-    if (!drawable->eventMask & GLX_BUFFER_SWAP_COMPLETE_INTEL_MASK)
+    if (!(drawable->eventMask & GLX_BUFFER_SWAP_COMPLETE_INTEL_MASK))
 	return;
 
     wire.type = __glXEventBase + GLX_BufferSwapComplete;