x.c | 2 +-

diff --git a/x.c b/x.c
index 5f4ea734b60e44845a5ac559cc7611cd8058765e..cd96575be257240b094888f9ca2bbdaaa0e3792a 100644
--- a/x.c
+++ b/x.c
@@ -415,7 +415,7 @@ 		code += btn - 1;
 
 	if (!IS_SET(MODE_MOUSEX10)) {
 		code += ((state & ShiftMask  ) ?  4 : 0)
-		      + ((state & Mod4Mask   ) ?  8 : 0)
+		      + ((state & Mod1Mask   ) ?  8 : 0) /* meta key: alt */
 		      + ((state & ControlMask) ? 16 : 0);
 	}