diff --git a/debug_toolbar/utils/tracking/db.py b/debug_toolbar/utils/tracking/db.py
index d64998476..a8a82cd9a 100644
--- a/debug_toolbar/utils/tracking/db.py
+++ b/debug_toolbar/utils/tracking/db.py
@@ -86,6 +86,8 @@ def _quote_expr(self, element):
             return repr(element)
 
     def _quote_params(self, params):
+        if params == None:
+            return None
         if isinstance(params, dict):
             return dict((key, self._quote_expr(value))
                             for key, value in params.iteritems())