diff --git a/ext/media/main.php b/ext/media/main.php
index a5b29eb6..69c4d306 100644
--- a/ext/media/main.php
+++ b/ext/media/main.php
@@ -277,6 +277,8 @@ class Media extends Extension
         } elseif ($event->image->length) {
             $s = ((int)($event->image->length / 100)) / 10;
             $event->replace('$size', "{$s}s");
+        } else {
+            $event->replace('$size', "unknown size");
         }
     }