diff --git a/cli.c b/cli.c
index 9a7128e3fc..51e71b48cf 100755
--- a/cli.c
+++ b/cli.c
@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <signal.h>
 #include <string.h>
+#include <ctype.h>
 /* For rl_filename_completion */
 #include "editline/readline/readline.h"
 /* For module directory */