diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 6af7e8e249..ee0d86a53e 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -71,7 +71,7 @@ class FormatStylePlaceholderCursor(Database.Cursor):
     def execute(self, query, params=None):
         if params is None: 
             params = []
-        args = [(':arg%s' % i) for i in range(num_params)]
+        args = [(':arg%s' % i) for i in range(len(params))]
         query = query % tuple(args)
         
         # cx can not execute the query with the closing ';'