diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index 1919b1e..4de9f71 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -96,24 +96,18 @@ MBTiles.findID = function(filepath, id, callback) {
 MBTiles.prototype._exists = function(table, callback) {
     if (typeof callback !== 'function') callback = noop;
 
-    if (this._schema) {
-        return callback(null, this._schema.indexOf(table) !== -1);
-    } else {
-        this._db.all(
-            'SELECT name FROM sqlite_master WHERE type IN (?, ?)',
-            'table',
-            'view',
-            function(err, rows) {
-                if (err) return callback(err);
-                this._schema = rows.map(function(r) { return r.name });
-                this._exists(table, callback);
-            }.bind(this)
-        );
-    }
+    if (this._schema) return callback(null, this._schema.indexOf(table) !== -1);
+
+    var sql = 'SELECT name FROM sqlite_master WHERE type IN ("table", "view")';
+    var mbtiles = this;
+    this._db.all(sql, function(err, rows) {
+        if (err) return callback(err);
+        mbtiles._schema = rows.map(function(r) { return r.name });
+        mbtiles._exists(table, callback);
+    });
 };
 
 // DB integrity check.
-//
 // - @param {Function(err)} callback
 MBTiles.prototype._integrity = function(callback) {
     if (typeof callback !== 'function') callback = noop;