diff --git a/src/run/display/x11.cr b/src/run/display/x11.cr
index 358f323..5aa7cf9 100644
--- a/src/run/display/x11.cr
+++ b/src/run/display/x11.cr
@@ -293,7 +293,7 @@ module Run
 			_key_event.type = type
 			_key_event.keycode = keycode
 			_key_event.state = state
-			if keycode < 9 # mouse button
+			if keycode <= 9 # mouse button
 				# pretend that keysym = keycode
 				@key_handler.not_nil!.call(_key_event, keycode.to_u64, nil)
 			else