diff --git a/extensions/firefox/install.rdf b/extensions/firefox/install.rdf
index 658985a61..dd86b3245 100644
--- a/extensions/firefox/install.rdf
+++ b/extensions/firefox/install.rdf
@@ -12,7 +12,7 @@
       <Description>
        <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
        <em:minVersion>6.0</em:minVersion>
-       <em:maxVersion>13.*</em:maxVersion>
+       <em:maxVersion>13.0a1</em:maxVersion>
      </Description>
     </em:targetApplication>
     <em:bootstrap>true</em:bootstrap>