diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index d598966..85d1d22 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -2231,11 +2231,15 @@
   call assert_fails('eval trim("  vim  ", " ", [])', 'E745:')
   call assert_fails('eval trim("  vim  ", " ", -1)', 'E475:')
   call assert_fails('eval trim("  vim  ", " ", 3)', 'E475:')
-  call assert_fails('eval trim("  vim  ", 0)', 'E1174:')
+  call assert_fails('eval trim("  vim  ", 0)', 'E1393:')
 
   let chars = join(map(range(1, 0x20) + [0xa0], {n -> n->nr2char()}), '')
   call assert_equal("x", trim(chars . "x" . chars))
 
+  call assert_equal("x", trim(chars . "x" . chars, v:none, 0))
+  call assert_equal("x" . chars, trim(chars . "x" . chars, v:none, 1))
+  call assert_equal(chars . "x", trim(chars . "x" . chars, v:none, 2))
+
   call assert_fails('let c=trim([])', 'E730:')
 endfunc