diff --git a/tests/test-basic.t b/tests/test-basic.t
--- a/tests/test-basic.t
+++ b/tests/test-basic.t
@@ -64,7 +64,7 @@
   > from mercurial import ui, hg, commands
   > myui = ui.ui.load()
   > repo = hg.repository(myui, path=b'.')
-  > commands.update(myui, repo, rev=0)
+  > commands.update(myui, repo, rev=b"0")
   > EOF
   $ hg up null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved