diff --git a/reference/image/functions/imagecolorat.xml b/reference/image/functions/imagecolorat.xml
index 150b22124c..7a41a6a4b5 100644
--- a/reference/image/functions/imagecolorat.xml
+++ b/reference/image/functions/imagecolorat.xml
@@ -51,8 +51,9 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
-   Returns the index of the color.
+   Returns the index of the color &return.falseforfailure;.
   </para>
+  &return.falseproblem;
  </refsect1>
  <refsect1 role="examples">
   &reftitle.examples;