diff --git a/common/file_helpers.py b/common/file_helpers.py
index c33ebac6f6..d4a0004108 100644
--- a/common/file_helpers.py
+++ b/common/file_helpers.py
@@ -5,6 +5,8 @@ from atomicwrites import AtomicWriter
 
 
 def mkdirs_exists_ok(path):
+  if path.startswith('http'):
+    raise ValueError('URL path')
   try:
     os.makedirs(path)
   except OSError: