diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index 72f1286..9a127a1 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -549,15 +549,12 @@ MBTiles.prototype.putTile = function(z, x, y, data, callback) {
 
     // Tilelive may pass us a data.key. If not, generate an md5
     // from the image buffer data.
-    var id;
-    if (data.key)
-        id = String(data.key);
-    else
-        id = crypto.createHash('md5').update(data).digest('hex');
-    if (!this._tileCache[id]) {
-        // This corresponds to the images table.
-        this._tileCache[id] = data;
-    }
+    var id = data.key
+        ? String(data.key)
+        : crypto.createHash('md5').update(data).digest('hex');
+
+    // This corresponds to the images table.
+    if (!this._tileCache[id]) this._tileCache[id] = data;
 
     // This corresponds to the map table.
     var coords = hash(z, x, y);
@@ -611,32 +608,38 @@ MBTiles.prototype.putGrid = function(z, x, y, data, callback) {
 
     // Preprocess grid data.
     var json = JSON.stringify({ grid: data.grid, keys: data.keys });
-    var id = data.id || crypto.createHash('md5').update(json).digest('hex');
-    if (!this._gridCache[id]) {
-        // This corresponds to the grid_utfgrid table.
-        var that = this;
-        Step(function() {
-            zlib.deflate(new Buffer(json, 'utf8'),this);
-        }, function(err,buffer) {
-            if (err) return callback(err);
-            that._gridCache[id] = buffer;
-            // This corresponds to the grid_key table.
-            that._keyCache[id] = Object.keys(data.data || {});
 
-            // This corresponds to the keymap table.
-            _(that._dataCache).extend(data.data || {});
-        }
-        );
-    }
+    // Tilelive may pass us a data.key. If not, generate an md5
+    // from the grid data.
+    var id = data.key
+        ? String(data.key)
+        : crypto.createHash('md5').update(json).digest('hex');
 
     // This corresponds to the map table.
     var coords = hash(z, x, y);
     if (!this._mapCache[coords]) this._mapCache[coords] = { z: z, x: x, y: y };
     this._mapCache[coords].grid_id = id;
 
-    // Only commit when we can insert at least batchSize rows.
-    if (++this._pending >= this._batchSize) return this._commit(callback);
-    else return callback(null);
+    var mbtiles = this;
+    Step(function() {
+        if (mbtiles._gridCache[id]) return this();
+        else zlib.deflate(new Buffer(json, 'utf8'), this);
+    }, function(err, buffer) {
+        if (err) throw err;
+        if (mbtiles._gridCache[id]) return this();
+        // grid_utfgrid table.
+        mbtiles._gridCache[id] = buffer;
+        // grid_key table.
+        mbtiles._keyCache[id] = Object.keys(data.data || {});
+        // keymap table.
+        _(mbtiles._dataCache).extend(data.data || {});
+        this();
+    }, function(err) {
+        if (err) return callback(err);
+        // Only commit when we can insert at least batchSize rows.
+        if (++this._pending >= this._batchSize) return this._commit(callback);
+        else return callback(null);
+    });
 };
 
 // Inserts a duplicate grid into the MBTiles store. Scheme is XYZ.