diff --git a/src/testdir/test_ruby.vim b/src/testdir/test_ruby.vim
index 100c9ea..eee2831 100644
--- a/src/testdir/test_ruby.vim
+++ b/src/testdir/test_ruby.vim
@@ -409,7 +409,10 @@
   ruby << trim
     Vim.command('let s ..= "D"')
   .
-  call assert_equal('ABCD', s)
+  ruby << trim eof
+    Vim.command('let s ..= "E"')
+  eof
+  call assert_equal('ABCDE', s)
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab