diff --git a/lib/src/widgets/controller.dart b/lib/src/widgets/controller.dart
index 0780b9ea..16e919e8 100644
--- a/lib/src/widgets/controller.dart
+++ b/lib/src/widgets/controller.dart
@@ -152,7 +152,9 @@ class QuillController extends ChangeNotifier {
       } else if (indent.value == 1 && !isIncrease) {
         formatAttribute = Attribute.clone(Attribute.indentL1, null);
       } else if (isIncrease) {
-        formatAttribute = Attribute.getIndentLevel(indent.value + 1);
+        if (indent.value < 5) {
+          formatAttribute = Attribute.getIndentLevel(indent.value + 1);
+        }
       } else {
         formatAttribute = Attribute.getIndentLevel(indent.value - 1);
       }