diff --git a/encoder/static.php b/encoder/static.php
index 4d47b3f..a620ac8 100755
--- a/encoder/static.php
+++ b/encoder/static.php
@@ -14,7 +14,7 @@ function setptsFromMs($ms)
     // format with up to 3 decimals (avoid scientific notation)
     $secFormatted = number_format($sec, 3, '.', '');
 
-    return "setpts=PTS+{$secFormatted}/TB";
+    return 'setpts=PTS+{$secFormatted}/TB';
 }
 
 function adelayFromMs($ms, $channels = 2)