diff --git a/pywb/rewrite/html_rewriter.py b/pywb/rewrite/html_rewriter.py
index 21989a29..e174c208 100644
--- a/pywb/rewrite/html_rewriter.py
+++ b/pywb/rewrite/html_rewriter.py
@@ -220,7 +220,7 @@ class HTMLRewriterMixin(object):
values = value.split(',')
values = [self._rewrite_url(v.strip()) for v in values]
- return ', '.join(values)
+ return ','.join(values)
def _rewrite_css(self, css_content):
if css_content: