diff --git a/scripts/gulpfiles/build_tasks.js b/scripts/gulpfiles/build_tasks.js
index cd66d8504..11fdcb2fc 100644
--- a/scripts/gulpfiles/build_tasks.js
+++ b/scripts/gulpfiles/build_tasks.js
@@ -191,7 +191,8 @@ function buildCompressed() {
     // Flatten all files so they're in the same directory, but ensure that
     // files with the same name don't conflict.
     .pipe(gulp.rename(function (p) {
-      var dirname = p.dirname.replace(new RegExp(path.sep, "g"), "-");
+      var dirname = p.dirname.replace(
+        new RegExp(path.sep.replace(/\\/, '\\\\'), "g"), "-");
       p.dirname = "";
       p.basename = dirname + "-" + p.basename;
     }))