diff --git a/reference/imagick/imagick/readimagefile.xml b/reference/imagick/imagick/readimagefile.xml
index 6f0a8926d0..8b710d7ab3 100644
--- a/reference/imagick/imagick/readimagefile.xml
+++ b/reference/imagick/imagick/readimagefile.xml
@@ -11,7 +11,7 @@
   <methodsynopsis>
    <type>bool</type><methodname>Imagick::readImageFile</methodname>
    <methodparam><type>resource</type><parameter>filehandle</parameter></methodparam>
-   <methodparam choice="opt"><type>string</type><parameter>fileName</parameter></methodparam>
+   <methodparam choice="opt"><type>string</type><parameter>fileName</parameter><initializer>null</initializer></methodparam>
   </methodsynopsis>
   &warn.undocumented.func;
   <para>