diff --git a/src/testdir/test_search.vim b/src/testdir/test_search.vim
index eaf9c23..f790c84 100644
--- a/src/testdir/test_search.vim
+++ b/src/testdir/test_search.vim
@@ -1682,6 +1682,8 @@
   call assert_fails("call search('\\(')", 'E54:')
   call assert_fails("call search('\\)')", 'E55:')
   call assert_fails("call search('\\z\\(\\)')", 'E66:')
+  call assert_fails("call search('\\z2')", 'E67:')
+  call assert_fails("call search('\\zx')", 'E867:')
   call assert_fails("call search('\\%[ab')", 'E69:')
   call assert_fails("call search('\\%[]')", 'E70:')
   call assert_fails("call search('\\%9999999999999999999999999999v')", 'E951:')