diff --git a/lib/SimpleSAML/Logger.php b/lib/SimpleSAML/Logger.php
index f838db1dfd0724c5e33a2af35f4d83dd5c960047..969f594354d5cb63409019376941738240857d61 100644
--- a/lib/SimpleSAML/Logger.php
+++ b/lib/SimpleSAML/Logger.php
@@ -423,7 +423,7 @@ class Logger
         if (self::$captureLog) {
             $ts = microtime(true);
             $msecs = (int) (($ts - (int) $ts) * 1000);
-            $ts = GMdate('H:i:s', $ts).sprintf('.%03d', $msecs).'Z';
+            $ts = gmdate('H:i:s', $ts).sprintf('.%03d', $msecs).'Z';
             self::$capturedLog[] = $ts.' '.$string;
         }