--- a/browser/extensions/flyweb/install.rdf.in
+++ b/browser/extensions/flyweb/install.rdf.in
@@ -8,16 +8,17 @@
 <RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
      xmlns:em="http://www.mozilla.org/2004/em-rdf#">
 
   <Description about="urn:mozilla:install-manifest">
     <em:id>flyweb@mozilla.org</em:id>
     <em:version>1.0.0</em:version>
     <em:type>2</em:type>
     <em:bootstrap>true</em:bootstrap>
+    <em:multiprocessCompatible>true</em:multiprocessCompatible>
 
     <!-- Target Application this theme can install into,
         with minimum and maximum supported versions. -->
     <em:targetApplication>
       <Description>
         <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
         <em:minVersion>@MOZ_APP_VERSION@</em:minVersion>
         <em:maxVersion>@MOZ_APP_MAXVERSION@</em:maxVersion>