1diff --git a/manuf/manuf.py b/manuf/manuf.py
2index e5e9193..09e9687 100755
3--- a/manuf/manuf.py
4+++ b/manuf/manuf.py
5@@ -65,8 +65,14 @@ class MacParser(object):
6 WFA_URL = "https://gitlab.com/wireshark/wireshark/raw/master/wka"
7
8 def __init__(self, manuf_name=None, update=False):
9- self._manuf_name = manuf_name or self.get_packaged_manuf_file_path()
10- if update:
11+ if manuf_name is not None:
12+ self._manuf_name = manuf_name
13+ self.external_db = True
14+ else:
15+ self._manuf_name = self.get_packaged_manuf_file_path()
16+ self.external_db = False
17+
18+ if update and self.external_db:
19 self.update()
20 else:
21 self.refresh()
22@@ -134,6 +140,9 @@ class MacParser(object):
23 URLError: If the download fails
24
25 """
26+ if manuf_url is None and not self.external_db:
27+ return
28+
29 if not manuf_url:
30 manuf_url = self.MANUF_URL
31 if not manuf_name: