--- a/mysys/get_password.c
+++ b/mysys/get_password.c
@@ -14,6 +14,8 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */
 
+#include <ctype.h>
+
 /*
 ** Ask for a password from tty
 ** This is an own file to avoid conflicts with curses