diff --git a/zarr/storage.py b/zarr/storage.py
index 656b05acf8..a3ac507c56 100644
--- a/zarr/storage.py
+++ b/zarr/storage.py
@@ -23,6 +23,7 @@
 import zipfile
 import shutil
 import atexit
+import errno
 import re
 import sys
 import json
@@ -745,8 +746,9 @@ def __setitem__(self, key, value):
         if not os.path.exists(dir_path):
             try:
                 os.makedirs(dir_path)
-            except Exception:
-                raise KeyError(key)
+            except OSError as e:
+                if e.errno != errno.EEXIST:
+                    raise KeyError(key)
 
         # write to temporary file
         temp_path = None
diff --git a/zarr/tests/data/store.zip b/zarr/tests/data/store.zip
new file mode 100644
index 0000000000..a36fd675b3
Binary files /dev/null and b/zarr/tests/data/store.zip differ
diff --git a/zarr/tests/data/store/foo b/zarr/tests/data/store/foo
new file mode 100644
index 0000000000..ba0e162e1c
--- /dev/null
+++ b/zarr/tests/data/store/foo
@@ -0,0 +1 @@
+bar
\ No newline at end of file