diff --git a/reference/info/functions/version-compare.xml b/reference/info/functions/version-compare.xml
index f5b92217f5..ad49b5b4c2 100644
--- a/reference/info/functions/version-compare.xml
+++ b/reference/info/functions/version-compare.xml
@@ -145,6 +145,15 @@ if (version_compare(PHP_VERSION, '5.0.0', '<')) {
     lower than their final release counterparts (like 5.3.0).
    </para>
   </note>
+  <note>
+   <para>
+    Special version strings such as <literal>alpha</literal> and
+    <literal>beta</literal> are case sensitive. Version strings from arbitrary
+    sources that do not adhere to the PHP standard may need to be lowercased
+    via <function>strtolower</function> before calling
+    <function>version_compare</function>.
+   </para>
+  </note>
  </refsect1>
 
  <refsect1 role="seealso">