diff --git a/h5p.classes.php b/h5p.classes.php
index 016dfd3..b20114d 100644
--- a/h5p.classes.php
+++ b/h5p.classes.php
@@ -4320,11 +4320,11 @@ class H5PContentValidator {
           if (preg_match('/^([-a-zA-Z]+)/', $attr, $match)) {
             $attrName = strtolower($match[1]);
             $skip = (
-              $attrname == 'style' ||
-              substr($attrname, 0, 2) == 'on' ||
-              substr($attrname, 0, 1) == '-' ||
+              $attrName == 'style' ||
+              substr($attrName, 0, 2) == 'on' ||
+              substr($attrName, 0, 1) == '-' ||
               // Ignore long attributes to avoid unnecessary processing overhead.
-              strlen($attrname) > 96
+              strlen($attrName) > 96
             );
             $working = $mode = 1;
             $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr);