Merge "Update tzdb version from 2019a to 2019b"
diff --git a/tools/ziputil.py b/tools/ziputil.py
index daee0cc..5b2b580 100644
--- a/tools/ziputil.py
+++ b/tools/ziputil.py
@@ -23,11 +23,15 @@
 
 from operator import attrgetter
 from zipfile import ZipFile
+import os
 
 
 def ZipCompare(path_a, path_b):
   """Compares the contents of two Zip archives, returns True if equal."""
 
+  if not os.path.isfile(path_a) or not os.path.isfile(path_b):
+    return False
+
   with ZipFile(path_a, 'r') as zip_a:
     info_a = zip_a.infolist()