diff --git a/ox/cache.py b/ox/cache.py
index 05830f1..882700a 100644
--- a/ox/cache.py
+++ b/ox/cache.py
@@ -121,7 +121,7 @@ get_url=read_url
 def save_url(url, filename, overwrite=False):
     if not os.path.exists(filename) or overwrite:
         dirname = os.path.dirname(filename)
-        if not os.path.exists(dirname):
+        if dirname and not os.path.exists(dirname):
             os.makedirs(dirname)
         data = read_url(url)
         with open(filename, 'wb') as f:
diff --git a/ox/net.py b/ox/net.py
index 8706247..200a2b4 100644
--- a/ox/net.py
+++ b/ox/net.py
@@ -113,7 +113,7 @@ get_url=read_url
 def save_url(url, filename, overwrite=False):
     if not os.path.exists(filename) or overwrite:
         dirname = os.path.dirname(filename)
-        if not os.path.exists(dirname):
+        if dirname and not os.path.exists(dirname):
             os.makedirs(dirname)
         data = read_url(url)
         with open(filename, 'wb') as f: