diff --git a/Makefile b/Makefile
index e6c703e37..d76fc3e04 100644
--- a/Makefile
+++ b/Makefile
@@ -283,6 +283,9 @@ extension: | production
 	@echo "AMO extension created: " $(FIREFOX_AMO_EXTENSION_NAME)
 	# List all files for mozilla-central
 	@cd $(FIREFOX_BUILD_DIR); find $(FIREFOX_EXTENSION_FILES) -type f > extension-files
+	# <em:maxVersion> must be set to "*" for mozilla-central
+	@sed -i.bak "s/em:maxVersion>[^<]*/em:maxVersion>*/" $(FIREFOX_BUILD_DIR)/install.rdf
+	@rm -f $(FIREFOX_BUILD_DIR)/*.bak
 
 	# Clear out everything in the chrome extension build directory
 	@rm -Rf $(CHROME_BUILD_DIR)
diff --git a/make.js b/make.js
index ea931988a..80e352e11 100755
--- a/make.js
+++ b/make.js
@@ -297,6 +297,8 @@ target.firefox = function() {
       extensionFiles += file+'\n';
   }
   extensionFiles.to('extension-files');
+  // <em:maxVersion> must be set to "*" for mozilla-central
+  sed('-i', /em:maxVersion>[^<]*/, 'em:maxVersion>*', 'install.rdf');
 };
 
 //