diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index d63bec4..4d4450d 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -86,13 +86,13 @@
 endfunc
 
 func Test_test_void()
-  call assert_fails('echo 1 == test_void()', 'E685:')
+  call assert_fails('echo 1 == test_void()', 'E1031:')
   if has('float')
-    call assert_fails('echo 1.0 == test_void()', 'E685:')
+    call assert_fails('echo 1.0 == test_void()', 'E1031:')
   endif
   call assert_fails('let x = json_encode(test_void())', 'E685:')
   call assert_fails('let x = copy(test_void())', 'E685:')
-  call assert_fails('let x = copy([test_void()])', 'E685:')
+  call assert_fails('let x = copy([test_void()])', 'E1031:')
 endfunc
 
 func Test_len()