diff --git a/h5p-development.class.php b/h5p-development.class.php
index 546ced0..6c891f9 100644
--- a/h5p-development.class.php
+++ b/h5p-development.class.php
@@ -78,7 +78,7 @@ class H5PDevelopment {
       }
 
       $library = json_decode($libraryJSON, TRUE);
-      if ($library === FALSE) {
+      if ($library === NULL) {
         continue; // Invalid JSON.
       }