diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 0dfd6f3..810b06c 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -1398,11 +1398,11 @@ String Value::Comments::get(CommentPlacement slot) const {
 }
 
 void Value::Comments::set(CommentPlacement slot, String comment) {
+  if (slot >= CommentPlacement::numberOfCommentPlacement) {
+    return;
+  }
   if (!ptr_) {
     ptr_ = std::unique_ptr<Array>(new Array());
-  }
-
-  if (slot < CommentPlacement::numberOfCommentPlacement) {
     (*ptr_)[slot] = std::move(comment);
   }
 }