diff --git a/src/calibre/ebooks/lrf/html/convert_from.py b/src/calibre/ebooks/lrf/html/convert_from.py
index adfa7b37eb..bd6ca9cab5 100644
--- a/src/calibre/ebooks/lrf/html/convert_from.py
+++ b/src/calibre/ebooks/lrf/html/convert_from.py
@@ -45,7 +45,9 @@ def update_css(ncss, ocss):
ocss[key] = ncss[key]
def munge_paths(basepath, url):
- purl = urlparse(unquote(url),)
+ purl = urlparse(unquote(url))
+ if purl[0] not in ('', 'file'):
+ return ('','')
path, fragment = purl[2], purl[5]
if path:
path = path.replace('/', os.sep)