diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index b5080d5..2bd53b5 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -174,7 +174,7 @@ MBTiles.prototype.getTile = function(z, x, y, callback) {
             } else {
                 var options = {
                     'Content-Type': MBTiles.utils.getMimeType(row.tile_data),
-                    'Last-Modified': mbtiles._stat.mtime,
+                    'Last-Modified': new Date(mbtiles._stat.mtime).toUTCString(),
                     'ETag': mbtiles._stat.size + '-' + Number(mbtiles._stat.mtime)
                 };
                 return callback(null, row.tile_data, options);
@@ -229,8 +229,12 @@ MBTiles.prototype.getGrid = function(z, x, y, callback) {
             } catch (err) {
                 return callback(new Error('Grid is invalid'));
             }
-
-            callback(null, result);
+            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);
         }
     );
 };