diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index 52b53e9d9..ece0606ae 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -827,26 +827,17 @@ class rcmail extends rcube
         }
 
         if ($absolute || $full) {
-            $prefix = '';
+            // add base path to this Roundcube installation
+            $base_path = preg_replace('![^/]+$!', '', strval($_SERVER['SCRIPT_NAME']));
+            if ($base_path == '') $base_path = '/';
+            $prefix = $base_path;
 
             // prepend protocol://hostname:port
             if ($full) {
-                $schema = 'http';
-                $default_port = 80;
-                if (rcube_utils::https_check()) {
-                    $schema = 'https';
-                    $default_port = 443;
-                }
-                $prefix = $schema . '://' . preg_replace('/:\d+$/', '', $_SERVER['HTTP_HOST']);
-                if ($_SERVER['SERVER_PORT'] != $default_port) {
-                  $prefix .= ':' . $_SERVER['SERVER_PORT'];
-                }
+                $prefix = rcube_utils::resolve_url($prefix);
             }
 
-            // add base path to this Roundcube installation
-            $base_path = preg_replace('![^/]+$!', '', strval($_SERVER['SCRIPT_NAME']));
-            if ($base_path == '') $base_path = '/';
-            $prefix .= $base_path;
+            $prefix = rtrim($prefix, '/') . '/';
         }
         else {
             $prefix = './';
diff --git a/program/lib/Roundcube/rcube_utils.php b/program/lib/Roundcube/rcube_utils.php
index 86d9eb2cc..ef303f8c1 100644
--- a/program/lib/Roundcube/rcube_utils.php
+++ b/program/lib/Roundcube/rcube_utils.php
@@ -1071,4 +1071,34 @@ class rcube_utils
             return $path[0] == DIRECTORY_SEPARATOR;
         }
     }
+
+    /**
+     * Resolve relative URL
+     *
+     * @param string $url Relative URL
+     *
+     * @return string Absolute URL
+     */
+    public static function resolve_url($url)
+    {
+        // prepend protocol://hostname:port
+        if (!preg_match('|^https?://|', $url)) {
+            $schema       = 'http';
+            $default_port = 80;
+
+            if (self::https_check()) {
+                $schema       = 'https';
+                $default_port = 443;
+            }
+
+            $prefix = $schema . '://' . preg_replace('/:\d+$/', '', $_SERVER['HTTP_HOST']);
+            if ($_SERVER['SERVER_PORT'] != $default_port) {
+                $prefix .= ':' . $_SERVER['SERVER_PORT'];
+            }
+
+            $url = $prefix . ($url[0] == '/' ? '' : '/') . $url;
+        }
+
+        return $url;
+    }
 }