include ctype.h

diff --git a/cstp.c b/cstp.c
index 49c9077..675a94d 100644 (file)
--- a/cstp.c
+++ b/cstp.c
@@ -24,6 +24,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <time.h>
+#include <ctype.h>
 
 #include <openssl/ssl.h>
 #include <openssl/err.h>