diff --git a/src/testdir/test_buffer.vim b/src/testdir/test_buffer.vim
index e54b633..8ef41e2 100644
--- a/src/testdir/test_buffer.vim
+++ b/src/testdir/test_buffer.vim
@@ -138,6 +138,7 @@
   %bwipe!
   call assert_fails('bdelete 5', 'E516:')
   call assert_fails('1,1bdelete 1 2', 'E488:')
+  call assert_fails('bdelete \)', 'E55:')
 
   " Deleting a unlisted and unloaded buffer
   edit Xfile1