diff --git a/src/Core/functions.php b/src/Core/functions.php
index 3a97ec1bd37..0fbd2069ada 100644
--- a/src/Core/functions.php
+++ b/src/Core/functions.php
@@ -64,6 +64,10 @@ function h($text, $double = true, $charset = null)
             }
         }
         if (is_string($double)) {
+            deprecationWarning(
+                'Passing charset string for 2nd argument is deprecated. ' .
+                'Use the 3rd argument instead.'
+            );
             $charset = $double;
         }