diff --git a/reference/strings/functions/strtr.xml b/reference/strings/functions/strtr.xml
index 0a1e2e0b33..8355269dc5 100644
--- a/reference/strings/functions/strtr.xml
+++ b/reference/strings/functions/strtr.xml
@@ -101,7 +101,9 @@
   <para>
    If <parameter>replace_pairs</parameter> contains a key which
    is an empty <type>string</type> (<literal>""</literal>),
-   &false; will be returned.
+   &false; will be returned. If the <parameter>str</parameter> is not a scalar
+   then it is not typecasted into a string, instead a warning is raised and 
+   &null; is returned. 
   </para>
  </refsect1>