diff --git a/src/testdir/test55.in b/src/testdir/test55.in
index 7b6f684..9e3c116 100644
--- a/src/testdir/test55.in
+++ b/src/testdir/test55.in
Binary files differ
diff --git a/src/testdir/test55.ok b/src/testdir/test55.ok
index 4e0303c..607a95ea 100644
--- a/src/testdir/test55.ok
+++ b/src/testdir/test55.ok
@@ -144,6 +144,9 @@
 Vim(put):E742: 
 No :unlet of variable in locked scope:
 Vim(unlet):E741: 
+No :let += of locked list variable:
+Vim(let):E741: 
+['a', 'b', 3]
 [1, 2, 3, 4]
 [1, 2, 3, 4]
 [1, 2, 3, 4]