diff --git a/src/libdraw/event.c b/src/libdraw/event.c
index da432db5..0b29a088 100644
--- a/src/libdraw/event.c
+++ b/src/libdraw/event.c
@@ -207,7 +207,8 @@ startrpc(int type)
 	Wsysmsg w;
 
 	w.type = type;
-	convW2M(&w, buf, sizeof buf);
+	if(convW2M(&w, buf, sizeof buf) == 0)
+		return nil;
 	return muxrpcstart(display->mux, buf);
 }