diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -296,7 +296,7 @@
         msg %= indent_string, exc.version, len(data)
         ui.write(msg)
     else:
-        msg = "%sversion: %s (%d bytes)\n"
+        msg = "%sversion: %d (%d bytes)\n"
         msg %= indent_string, version, len(data)
         ui.write(msg)
         fm = ui.formatter('debugobsolete', opts)