1 files changed, 2 insertions, 0 deletions

diff --git a/plugins/check_tcp.c b/plugins/check_tcp.c
index b024821e..9e62638b 100644
--- a/plugins/check_tcp.c
+++ b/plugins/check_tcp.c
@@ -32,6 +32,8 @@ char *progname;
 const char *copyright = "1999-2008";
 const char *email = "nagiosplug-devel@lists.sourceforge.net";
 
+#include <ctype.h>
+
 #include "common.h"
 #include "netutils.h"
 #include "utils.h"