diff --git a/src/getchar.c b/src/getchar.c
index 7a1ef8c..2068ca4 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -3594,7 +3594,7 @@
 	 */
 	if (got_int)
 	{
-#define DUM_LEN MAXMAPLEN * 3 + 3
+#define DUM_LEN (MAXMAPLEN * 3 + 3)
 	    char_u	dum[DUM_LEN + 1];
 
 	    for (;;)