diff --git a/src/server/util.js b/src/server/util.js
index 21e3c0d7..31a288d2 100644
--- a/src/server/util.js
+++ b/src/server/util.js
@@ -1,5 +1,5 @@
 /* @flow */
 
-export const isJS = (file: string): boolean => /\.js($|\?)/.test(file)
+export const isJS = (file: string): boolean => /\.js(\?[^.]+)?$/.test(file)
 
-export const isCSS = (file: string): boolean => /\.css($|\?)/.test(file)
+export const isCSS = (file: string): boolean => /\.css(\?[^.]+)?$/.test(file)