diff --git a/lib/motion/project/target/extension_target.rb b/lib/motion/project/target/extension_target.rb
index 52c9ad6d..a12347ac 100644
--- a/lib/motion/project/target/extension_target.rb
+++ b/lib/motion/project/target/extension_target.rb
@@ -37,19 +37,6 @@ module Motion; module Project
       if !File.exist?(extension_path) or File.mtime(src_path) > File.mtime(extension_path)
         App.info 'Copy', src_path
         FileUtils.cp_r(src_path, dest_path)
-
-        # At build time Extensions do not know the bundle indentifier of its
-        # parent app, so we have to modify their Info.plist later
-        extension_dir = File.join(destination_dir, extension_name)
-        info_plist = File.join(extension_dir, 'Info.plist')
-        extension_bundle_name = `/usr/libexec/PlistBuddy -c "print CFBundleName" "#{info_plist}"`.strip
-        extension_bundle_indentifer = `/usr/libexec/PlistBuddy -c "print CFBundleIdentifier" "#{info_plist}"`.strip
-        if extension_bundle_indentifer.include?(".watchkitextension")
-          extension_bundle_indentifer = "#{@config.identifier}.watchkitextension"
-        else
-          extension_bundle_indentifer = "#{@config.identifier}.#{extension_bundle_name}"
-        end
-        `/usr/libexec/PlistBuddy -c "set CFBundleIdentifier #{extension_bundle_indentifer}" "#{info_plist}"`
       end
     end
 
diff --git a/lib/motion/project/template/ios-extension-config.rb b/lib/motion/project/template/ios-extension-config.rb
index 42c07124..72bf76f6 100644
--- a/lib/motion/project/template/ios-extension-config.rb
+++ b/lib/motion/project/template/ios-extension-config.rb
@@ -182,6 +182,16 @@ module Motion; module Project;
       ary.map { |family| device_family_int(family) }
     end
 
+    # @todo Is it correct that a bundle identifier may contain spaces? Because
+    #       the `bundle_name` definitely can contain spaces.
+    #
+    # @return [String] The bundle identifier of the application extension based
+    #         on the bundle identifier of the host application.
+    #
+    def identifier
+      ENV['RM_TARGET_HOST_APP_IDENTIFIER'] + '.' + bundle_name
+    end
+
     def app_bundle(platform)
       File.join(versionized_build_dir(platform), bundle_name + '.appex')
     end