diff --git a/py/_plugin/pytest_assertion.py b/py/_plugin/pytest_assertion.py
index 226da79c7..9e6355f41 100644
--- a/py/_plugin/pytest_assertion.py
+++ b/py/_plugin/pytest_assertion.py
@@ -89,7 +89,7 @@ def _compare_eq_sequence(left, right):
                         'first extra item: %s' % left[len(right)]]
     elif len(left) < len(right):
         explanation += ['Right contains more items, '
-                        'first extra item: %s' % right[len(right)]]
+                        'first extra item: %s' % right[len(left)]]
     return explanation + _pprint_diff(left, right)
 
 
diff --git a/testing/plugin/test_pytest_assertion.py b/testing/plugin/test_pytest_assertion.py
index 9d750896f..abada10b2 100644
--- a/testing/plugin/test_pytest_assertion.py
+++ b/testing/plugin/test_pytest_assertion.py
@@ -117,6 +117,12 @@ class TestAssertCompare:
         expl = plugin.pytest_assert_binrepr('==', [0, 1], [0, 2])
         assert len(expl) > 1
 
+    def test_list_different_lenghts(self):
+        expl = plugin.pytest_assert_binrepr('==', [0, 1], [0, 1, 2])
+        assert len(expl) > 1
+        expl = plugin.pytest_assert_binrepr('==', [0, 1, 2], [0, 1])
+        assert len(expl) > 1
+
     def test_dict(self):
         expl = plugin.pytest_assert_binrepr('==', {'a': 0}, {'a': 1})
         assert len(expl) > 1