diff --git a/src/wp-admin/includes/class-pclzip.php b/src/wp-admin/includes/class-pclzip.php
index 658fda5f22495..f1128d900c9e6 100644
--- a/src/wp-admin/includes/class-pclzip.php
+++ b/src/wp-admin/includes/class-pclzip.php
@@ -5714,7 +5714,7 @@ function PclZipUtilOptionText($p_option)
   // --------------------------------------------------------------------------------
   function PclZipUtilTranslateWinPath($p_path, $p_remove_disk_letter=true)
   {
-    if (stristr(php_uname(), 'windows')) {
+    if (PHP_OS_FAMILY == 'Windows') {
       // ----- Look for potential disk letter
       if (($p_remove_disk_letter) && (($v_position = strpos($p_path, ':')) != false)) {
           $p_path = substr($p_path, $v_position+1);