diff --git a/lib/extras.py b/lib/extras.py
index 2f027144..e828a6ce 100644
--- a/lib/extras.py
+++ b/lib/extras.py
@@ -971,12 +971,12 @@ def register_composite(name, conn_or_curs, globally=False, factory=None):
 class Insert_Values(list):
     def __init__(self, list_of_tuples):
         assert isinstance(list_of_tuples, list), 'Insert_Values argument must be a list'
-        tuples_lenght = set()
+        tuples_length = set()
         for t in list_of_tuples:
             assert isinstance(t, tuple), 'The Insert_Values list elements must all be tuples'
-            tuples_lenght.add(len(t))
-        assert len(tuples_lenght) > 0, 'The Insert_Values List must not be empty'
-        assert len(tuples_lenght) == 1, 'All Insert_Values tuples must have the same length'
+            tuples_length.add(len(t))
+        assert len(tuples_length) > 0, 'The Insert_Values List must not be empty'
+        assert len(tuples_length) == 1, 'All Insert_Values tuples must have the same length'
         self._list_of_tuples = list_of_tuples
     def __str__(self):
         return str(self._list_of_tuples)
@@ -988,7 +988,6 @@ def adapt_insert_values(values):
 def register_insert_values():
     _ext.register_adapter(Insert_Values, adapt_insert_values)
 
-
 # expose the json adaptation stuff into the module
 from psycopg2._json import json, Json, register_json
 from psycopg2._json import register_default_json, register_default_jsonb