diff --git a/ox/cache.py b/ox/cache.py
index 6b2f8d3..e5f3dc4 100644
--- a/ox/cache.py
+++ b/ox/cache.py
@@ -363,11 +363,11 @@ class FileCache(Cache):
         if not info['only_headers']:
             if info['compressed']:
                 data = zlib.compress(data)
-            elif not isinstance(data, str):
+            elif not isinstance(data, bytes):
                 data = data.encode('utf-8')
             with open(f, 'wb') as _f:
                 _f.write(data)
-        with open(i, 'wb') as _i:
+        with open(i, 'w') as _i:
             json.dump(info, _i)
 
 if cache_path().startswith('fs:'):