diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 316fb42..e5f521c 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -218,6 +218,7 @@
   call assert_equal(15, 0o17)
   call assert_equal(15, 0O17)
   call assert_equal(18, 018)
+  call assert_equal(511, 0o777)
   call assert_equal(64, 0b1'00'00'00)
   call assert_equal(1048576, 0x10'00'00)
   call assert_equal(32768, 0o10'00'00)
@@ -233,6 +234,7 @@
   call assert_equal(15, 0o17)
   call assert_equal(15, 0O17)
   call assert_equal(18, 018)
+  call assert_equal(511, 0o777)
 endfunc
 
 func Test_scriptversion_fail()