diff --git a/h5bp/location/cache-busting.conf b/h5bp/location/cache-busting.conf
index 6afe34a..9162ca9 100644
--- a/h5bp/location/cache-busting.conf
+++ b/h5bp/location/cache-busting.conf
@@ -5,6 +5,6 @@
 # Read also this: github.com/h5bp/html5-boilerplate/wiki/cachebusting
 # This is not included by default, because it'd be better if you use the build
 # script to manage the file names.
-location ~* (.+)\.(?:\d+)\.(js|css|png|jpg|jpeg|gif)$ {
+location ~* (.+)\.(?:[0-9A-Za-z]+)\.(js|css|png|jpg|jpeg|gif)$ {
   try_files $uri $1.$2;
 }