diff --git a/mod_websocket.c b/mod_websocket.c
index a487eac..fc1081a 100644
--- a/mod_websocket.c
+++ b/mod_websocket.c
@@ -932,7 +932,7 @@ static const char *construct_request_origin(request_rec *r)
     const char *hostname = r->hostname;
     apr_port_t port = ap_get_server_port(r);
 
-    if (ap_strchr_c(hostname, ':')) {
+    if ((hostname!=NULL)&&(ap_strchr_c(hostname, ':'))) {
         /* IPv6 hostnames need to be bracketed. */
         hostname = apr_pstrcat(r->pool, "[", hostname, "]", NULL);
     }