1 files changed, 4 insertions, 0 deletions
diff --git a/lib/url.c b/lib/url.c
index 85cdd5336..47fc66aed 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1438,8 +1438,12 @@ void Curl_verboseconnect(struct connectdata *conn)
  */
 bool Curl_is_ASCII_name(const char *hostname)
 {
+  /* get an UNSIGNED local version of the pointer */
   const unsigned char *ch = (const unsigned char *)hostname;
 
+  if(!hostname) /* bad input, consider it ASCII! */
+    return TRUE;
+
   while(*ch) {
     if(*ch++ & 0x80)
       return FALSE;