diff --git a/src/testdir/test_python3.vim b/src/testdir/test_python3.vim
index 97f797e..cd5ac9c 100644
--- a/src/testdir/test_python3.vim
+++ b/src/testdir/test_python3.vim
@@ -170,11 +170,18 @@
 
 func Test_unicode()
   " this crashed Vim once
+  let save_tenc = &tenc
+  set tenc=
+
   set encoding=utf32
   py3 print('hello')
+
   set encoding=debug
   py3 print('hello')
+
   set encoding=euc-tw
   py3 print('hello')
+
   set encoding=utf8
+  let &tenc = save_tenc
 endfunc