diff --git a/core/editor.js b/core/editor.js
index d5f564d64a..5dd1c70c77 100644
--- a/core/editor.js
+++ b/core/editor.js
@@ -230,7 +230,7 @@ function normalizeDelta(delta) {
       delete attributes['image'];
       return delta.insert({ image: op.attributes.image }, attributes);
     }
-    if (op.attributes != null && (op.attributes.list || op.attributes.bullet)) {
+    if (op.attributes != null && (op.attributes.list === true || op.attributes.bullet === true)) {
       op = clone(op);
       if (op.attributes.list) {
         op.attributes.list = 'ordered';