diff --git a/src/term.c b/src/term.c
index 672a09cd..839e5608 100644
--- a/src/term.c
+++ b/src/term.c
@@ -20,6 +20,7 @@
 
 #include "ac_cfg.h"
 
+#include <ctype.h>
 #include <string.h>
 #include <stdio.h>
 #include <stdint.h>