diff --git a/reference/image/book.xml b/reference/image/book.xml
index 25c4cb8378..9afeae331a 100644
--- a/reference/image/book.xml
+++ b/reference/image/book.xml
@@ -77,7 +77,7 @@
        <entry>PNG</entry>
        <entry>&true;</entry>
        <entry>&true;</entry>
-       <entry>&nbsp;</entry>
+       <entry></entry>
       </row>
       <row>
        <entry>GIF</entry>