diff --git a/makeidx.py b/makeidx.py
index 16ac17d..090c4fe 100644
--- a/makeidx.py
+++ b/makeidx.py
@@ -10,7 +10,7 @@ import argparse
 import datetime
 import json
 
-DATA_BACKGROUND = re.compile(r"data-background='(.*?)'")
+DATA_BACKGROUND = re.compile(r"data-background=['\"](.*?)['\"]")
 PRES_TITLE = re.compile(r"<h1.*?>(.*?)</h1>")