diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index 2ace481..f7460b5 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -215,26 +215,25 @@ MBTiles.prototype.getGrid = function(z, x, y, callback) {
             }
             if (err) return callback(err);
 
-            try {
-                var grid = zlib.inflate(
-                           !Buffer.isBuffer(row.grid)
+            zlib.inflate(!Buffer.isBuffer(row.grid)
                            ? new Buffer(row.grid, 'binary')
                            : row.grid
-                       ).toString();
-                var data = rows.reduce(function(memo, r) {
-                        memo[r.key_name] = JSON.parse(r.key_json);
-                        return memo;
-                    }, {});
-                var result = _(JSON.parse(grid)).extend({ data: data });
-            } catch (err) {
-                return callback(new Error('Grid is invalid'));
-            }
-            var options = {
-                'Content-Type': 'text/javascript',
-                'Last-Modified': new Date(that._stat.mtime).toUTCString(),
-                'ETag': that._stat.size + '-' + Number(that._stat.mtime)
-            };
-            callback(null, result, options);
+                         , function(err,buffer) {
+                                if (err) {
+                                    return callback(new Error('Grid is invalid:' + err.message));
+                                }
+                                var data = rows.reduce(function(memo, r) {
+                                        memo[r.key_name] = JSON.parse(r.key_json);
+                                        return memo;
+                                    }, {});
+                                var result = _(JSON.parse(buffer.toString())).extend({ data: data });
+                                var options = {
+                                    'Content-Type': 'text/javascript',
+                                    'Last-Modified': new Date(that._stat.mtime).toUTCString(),
+                                    'ETag': that._stat.size + '-' + Number(that._stat.mtime)
+                                };
+                                callback(null, result, options);
+            });
         }
     );
 };
@@ -582,13 +581,19 @@ MBTiles.prototype.putGrid = function(z, x, y, data, callback) {
     var id = data.id || crypto.createHash('md5').update(json).digest('hex');
     if (!this._gridCache[id]) {
         // This corresponds to the grid_utfgrid table.
-        this._gridCache[id] = zlib.deflate(new Buffer(json, 'utf8'));
+        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 grid_key table.
-        this._keyCache[id] = Object.keys(data.data || {});
-
-        // This corresponds to the keymap table.
-        _(this._dataCache).extend(data.data || {});
+            // This corresponds to the keymap table.
+            _(that._dataCache).extend(data.data || {});
+        }
+        );
     }
 
     // This corresponds to the map table.
diff --git a/package.json b/package.json
index 3cde336..ab77dae 100644
--- a/package.json
+++ b/package.json
@@ -30,14 +30,13 @@
     ],
     "dependencies": {
         "optimist": "0.2.x",
-        "sqlite3": "~2.0.17",
+        "sqlite3": "~2.1.1",
         "step": "0.0.x",
         "sphericalmercator": "1.0.x",
-        "underscore": "1.1.x",
-        "zlib": "1.0.x"
+        "underscore": "1.1.x"
     },
     "engines": {
-        "node": ">= 0.4.0"
+        "node": ">= 0.6.0"
     },
     "scripts": {
         "test": "expresso"