diff --git a/lib/http.h b/lib/http.h
index 48adc5231..bfd73b5f6 100644
--- a/lib/http.h
+++ b/lib/http.h
@@ -25,7 +25,8 @@
  *****************************************************************************/
 
 /* ftp can use this as well */
-CURLcode Curl_ConnectHTTPProxyTunnel(struct UrlData *data, int tunnelsocket,
+CURLcode Curl_ConnectHTTPProxyTunnel(struct connectdata *conn,
+                                     int tunnelsocket,
                                      char *hostname, int remote_port);
 
 /* protocol-specific functions set up to be called by the main engine */