diff --git a/test/lisp/vc/vc-tests/vc-tests.el b/test/lisp/vc/vc-tests/vc-tests.el
index a64bee00de2..a9b4653ac9b 100644
--- a/test/lisp/vc/vc-tests/vc-tests.el
+++ b/test/lisp/vc/vc-tests/vc-tests.el
@@ -436,9 +436,12 @@ This checks also `vc-backend' and `vc-responsible-backend'."
               ;; nil: Git Mtn
               ;; "0": Bzr CVS Hg SRC SVN
               ;; "1.1": RCS SCCS
+              ;; "0000000000000000000000000000000000000000": Hg
               ;; "-1": Hg versions before 5 (probably)
               (message "vc-working-revision4 %s" (vc-working-revision tmp-name))
-              (should (member (vc-working-revision tmp-name) '(nil "0" "1.1" "-1")))
+              (should (member (vc-working-revision tmp-name)
+                              '(nil "0" "1.1" "-1"
+                                    "0000000000000000000000000000000000000000")))
 
               ;; TODO: Call `vc-checkin', and check the resulting
               ;; working revision.  None of the return values should be