diff --git a/src/common/_Content.js b/src/common/_Content.js
index 91facf0..48847a6 100644
--- a/src/common/_Content.js
+++ b/src/common/_Content.js
@@ -488,7 +488,9 @@ class _Content {
    */
   reviseImages(callback) {
     if (this.isImagesRevised) {
-      callback();
+      if (callback) {
+        callback();
+      }
       return;
     }