diff --git a/core/includes/install.inc b/core/includes/install.inc
index ebcab90..066884c 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -176,34 +176,37 @@ function drupal_get_database_types() {
  * @throws Exception
  */
 function drupal_clear_opcode_cache($filepath) {
+  // This setting can be On/Off or 1/0, but when the setting is Off
+  // the returned value is an empty string instead of 0.
+  $empty_values = array("", 0);
   clearstatcache(TRUE, $filepath);
 
   try {
-    if (function_exists('opcache_invalidate')) {
+    if (extension_loaded('Zend OPcache')) {
       $timestamps = ini_get('opcache.validate_timestamps');
       if (!$timestamps || ($timestamps && ini_get('opcache.revalidate_freq') != 0)) {
         opcache_invalidate($filepath);
       }
     }
-    if (function_exists('apc_delete_file') && ini_get('apc.stat') == 0) {
+    if (extension_loaded('apc') && in_array(ini_get('apc.stat'), $empty_values)) {
       apc_delete_file($filepath);
     }
-    if (function_exists('wincache_refresh_if_changed')) {
-      if (ini_get('wincache.fcndetect') == 0 || ini_get('wincache.chkinterval') == 0) {
+    if (extension_loaded('wincache')) {
+      if (in_array(ini_get('wincache.fcndetect'), $empty_values) || ini_get('wincache.chkinterval') == 0) {
         wincache_refresh_if_changed(array($filepath));
       }
     }
-    if (function_exists('xcache_clear_cache')) {
-      // Use @ error suppression.
-      @xcache_clear_cache(XC_TYPE_PHP);
+    if (extension_loaded('XCache') && in_array(ini_get('xcache.stat'), $empty_values)) {
+      for ($i = 0; $i < xcache_count(XC_TYPE_PHP); $i++) {
+        xcache_clear_cache(XC_TYPE_PHP, $i);
+      }
     }
-    if (function_exists('eaccelerator_clear')) {
-      // Use @ error suppression.
-      @eaccelerator_clear();
+    if (extension_loaded('eaccelerator')) {
+      eaccelerator_clear();
     }
   }
   catch (Exception $e) {
-    throw new Exception(t('Failed to clear the opcode cache for %settings. For the duration of the installation it is recommended to either disable the opcode cache, or reconfigure it to allow code changes to be seen immediately.', array('%settings' => $settings_file)));
+    throw new Exception(t('Failed to clear the opcode cache for %file. For the duration of the installation it is recommended to either disable the opcode cache, or reconfigure it to allow code changes to be seen immediately.', array('%file' => $filepath)));
   }
 }