diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index cf7a15d..f1d7e03 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -546,7 +546,7 @@ MBTiles.prototype._commit = function(callback) {
             // Insert grid_key.
             var keys = mbtiles._db.prepare('INSERT OR IGNORE INTO grid_key (grid_id, key_name) VALUES (?, ?)');
             for (var id in mbtiles._keyCache) {
-                mbtiles._keyCache.forEach(function(key) {
+                mbtiles._keyCache[id].forEach(function(key) {
                     keys.run(id, key);
                 });
             }
@@ -661,7 +661,7 @@ MBTiles.prototype.putGrid = function(z, x, y, data, callback) {
         this._keyCache[id] = Object.keys(data.data || {});
 
         // This corresponds to the keymap table.
-        this._dataCache.extend(data.data || {});
+        _(this._dataCache).extend(data.data || {});
     }
 
     // This corresponds to the map table.