diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 478c394..957671c 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -2060,6 +2060,12 @@
     total += nr
   endfor
   assert_equal(6, total)
+
+  var res = ""
+  for [n: number, s: string] in [[1, 'a'], [2, 'b']]
+    res ..= n .. s
+  endfor
+  assert_equal('1a2b', res)
 enddef
 
 def Test_for_loop_fails()