index 3995cc3..2fd6ae6 100644
--- morse.c
+++ morse.c
@@ -18,6 +18,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
 
 #include <stdio.h>
+#include <ctype.h>
 
 #include "cw.h"
 #include "morse.h"