diff --git a/inc/HTTPClient.php b/inc/HTTPClient.php
index 4352bcb97b70478031539bf556902d3f1e16ca22..6ac67f159a7f15cd7308746691d76df4b3e5ef76 100644
--- a/inc/HTTPClient.php
+++ b/inc/HTTPClient.php
@@ -35,6 +35,19 @@ class DokuHTTPClient extends HTTPClient {
         $this->proxy_pass   = conf_decodeString($conf['proxy']['pass']);
         $this->proxy_ssl    = $conf['proxy']['ssl'];
         $this->proxy_except = $conf['proxy']['except'];
+
+        // allow enabling debugging via URL parameter (if debugging allowed)
+        if($conf['allowdebug']) {
+            if(
+                isset($_REQUEST['httpdebug']) ||
+                (
+                    isset($_SERVER['HTTP_REFERER']) &&
+                    strpos($_SERVER['HTTP_REFERER'], 'httpdebug') !== false
+                )
+            ) {
+                $this->debug = true;
+            }
+        }
     }