diff --git a/src/testdir/test_substitute.vim b/src/testdir/test_substitute.vim
index 35b6b8a..2622749 100644
--- a/src/testdir/test_substitute.vim
+++ b/src/testdir/test_substitute.vim
@@ -811,6 +811,10 @@
   s\&green&
   call assert_equal('amber green yellow white green', getline(1))
   close!
+
+  call assert_fails('vim9cmd s\/white/', 'E1270:')
+  call assert_fails('vim9cmd s\?white?', 'E1270:')
+  call assert_fails('vim9cmd s\&white&', 'E1270:')
 endfunc
 
 " Test for substitute with the new text longer than the original text