diff --git a/src/php/exec/escapeshellarg.js b/src/php/exec/escapeshellarg.js
index 522b13dbb1..1dcd44863d 100644
--- a/src/php/exec/escapeshellarg.js
+++ b/src/php/exec/escapeshellarg.js
@@ -1,5 +1,8 @@
 module.exports = function escapeshellarg (arg) {
   //  discuss at: https://locutus.io/php/escapeshellarg/
+  // Warning: this function emulates escapeshellarg() for php-running-on-linux
+  // the function behaves differently when running on Windows, which is not covered by this code.
+  // 
   // original by: Felix Geisendoerfer (https://www.debuggable.com/felix)
   // improved by: Brett Zamir (https://brett-zamir.me)
   //   example 1: escapeshellarg("kevin's birthday")