diff --git a/lib/classes/JsonApi/Routes/Blubber/CommentsCreate.php b/lib/classes/JsonApi/Routes/Blubber/CommentsCreate.php
index 6d9502032eb94e9f9b1023ea82907c85baf52e33..2e25d3fb5279a5e3bc551dcb5f9afb35ef6ecd23 100644
--- a/lib/classes/JsonApi/Routes/Blubber/CommentsCreate.php
+++ b/lib/classes/JsonApi/Routes/Blubber/CommentsCreate.php
@@ -54,9 +54,14 @@ class CommentsCreate extends JsonApiController
 
     protected function validateResourceDocument($json, $id = null)
     {
-        if (empty(self::arrayGet($json, 'data.attributes.content'))) {
+        if (!self::arrayHas($json, 'data.attributes.content')) {
+            return 'No comment provided';
+        }
+
+        if (mb_strlen(trim(self::arrayGet($json, 'data.attributes.content'))) === 0) {
             return 'Comment should not be empty.';
         }
+
         if (!$id && !$this->getThreadFromJson($json)) {
             return 'Invalid `block` relationship.';
         }