diff --git a/reference/array/functions/array-key-exists.xml b/reference/array/functions/array-key-exists.xml
index e663147dea..f9ef2b1e4a 100644
--- a/reference/array/functions/array-key-exists.xml
+++ b/reference/array/functions/array-key-exists.xml
@@ -50,6 +50,12 @@
   <para>
    &return.success;
   </para>
+  <caution>
+   <para>
+    <function>array_key_exists</function> will search for the kyes in first dimention only.
+    Nested kyes in multidimensional arrays will not be found.
+   </para>
+  </caution>
  </refsect1>
 
  <refsect1 role="examples">