diff --git a/h5p.classes.php b/h5p.classes.php
index 3c27445..ccc7425 100644
--- a/h5p.classes.php
+++ b/h5p.classes.php
@@ -325,7 +325,7 @@ class H5PValidator {
     'h' => '/^[0-9]{1,4}$/',
     'embedTypes' => array('iframe', 'div'),
     'fullscreen' => '/^(0|1)$/',
-    'coreVersion' => array(
+    'coreApi' => array(
       'majorVersion' => '/^[0-9]{1,5}$/',
       'minorVersion' => '/^[0-9]{1,5}$/',
     ),
@@ -656,17 +656,17 @@ class H5PValidator {
     // Test library core version requirement.  If no requirement is set,
     // this implicitly means 1.0, which shall work on newer versions
     // too.
-    if (isset($h5pData['coreVersion']) && !empty($h5pData['coreVersion'])) {
-      if (($h5pData['coreVersion']['majorVersion'] > H5PCore::$coreVersion['majorVersion']) ||
-          (($h5pData['coreVersion']['majorVersion'] == H5PCore::$coreVersion['majorVersion']) &&
-            ($h5pData['coreVersion']['minorVersion'] > H5PCore::$coreVersion['minorVersion'])))
+    if (isset($h5pData['coreApi']) && !empty($h5pData['coreApi'])) {
+      if (($h5pData['coreApi']['majorVersion'] > H5PCore::$coreApi['majorVersion']) ||
+          (($h5pData['coreApi']['majorVersion'] == H5PCore::$coreApi['majorVersion']) &&
+            ($h5pData['coreApi']['minorVersion'] > H5PCore::$coreApi['minorVersion'])))
       {
         $this->h5pF->setErrorMessage(
-          $this->h5pF->t('The library "%library_name" requires H5P %requiredVersion, but only H5P %coreVersion is installed.',
+          $this->h5pF->t('The library "%library_name" requires H5P %requiredVersion, but only H5P %coreApi is installed.',
           array(
             '%library_name' => $library_name,
-            '%requiredVersion' => $h5pData['coreVersion']['majorVersion'] . '.' . $h5pData['coreVersion']['minorVersion'],
-            '%coreVersion' => H5PCore::$coreVersion['majorVersion'] . '.' . H5PCore::$coreVersion['minorVersion']
+            '%requiredVersion' => $h5pData['coreApi']['majorVersion'] . '.' . $h5pData['coreApi']['minorVersion'],
+            '%coreApi' => H5PCore::$coreApi['majorVersion'] . '.' . H5PCore::$coreApi['minorVersion']
           )));
         $valid = false;
       }
@@ -1224,7 +1224,7 @@ Class H5PExport {
  * Functions and storage shared by the other H5P classes
  */
 class H5PCore {
-  public static $coreVersion = array(
+  public static $coreApi = array(
     'majorVersion' => 1,
     'minorVersion' => 0
   );