diff --git a/src/CredentialSource/AwsNativeSource.php b/src/CredentialSource/AwsNativeSource.php
index 3a8c20eaa6..460d9e5ea4 100644
--- a/src/CredentialSource/AwsNativeSource.php
+++ b/src/CredentialSource/AwsNativeSource.php
@@ -153,8 +153,8 @@ public static function getSignedRequestHeaders(
         $service = 'sts';
 
         # Create a date for headers and the credential string in ISO-8601 format
-        $amzdate = date('Ymd\THis\Z');
-        $datestamp = date('Ymd'); # Date w/o time, used in credential scope
+        $amzdate = gmdate('Ymd\THis\Z');
+        $datestamp = gmdate('Ymd'); # Date w/o time, used in credential scope
 
         # Create the canonical headers and signed headers. Header names
         # must be trimmed and lowercase, and sorted in code point order from