diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index cf3362d..a05d010 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -804,6 +804,12 @@
   call feedkeys(":topleft new\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"topleft new", @:)
 
+  " completion for vim9 and legacy commands
+  call feedkeys(":vim9 call strle\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"vim9 call strlen(", @:)
+  call feedkeys(":legac call strle\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"legac call strlen(", @:)
+
   " completion for the :match command
   call feedkeys(":match Search /pat/\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"match Search /pat/\<C-A>", @:)