diff --git a/src/learn.c b/src/learn.c
index 76a7663a7..22bc27d0e 100644
--- a/src/learn.c
+++ b/src/learn.c
@@ -28,6 +28,7 @@
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/stat.h>
+#include <ctype.h>
 #include "tty.h"
 #include "mad.h"
 #include "util.h"	/* Needed for the externs and convert_controls */