diff --git a/lib/utils.js b/lib/utils.js
index ff6b226f..177ae97b 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -48,6 +48,9 @@ var prepareValue = function(val, seen) {
   if(typeof val === 'object') {
     return prepareObject(val, seen);
   }
+  if (typeof val === 'undefined') {
+    throw new Error('SQL queries with undefined where clause option');
+  }
   return val.toString();
 };