if test -n "$branch"
        then
                old_branch_name=`expr "z$oldbranch" : 'zrefs/heads/\(.*\)'`
-               GIT_DIR="$GIT_DIR" git symbolic-ref -m "checkout: moving from $old_branch_name to $branch" HEAD "refs/heads/$branch"
+               GIT_DIR="$GIT_DIR" git symbolic-ref -m "checkout: moving from ${old_branch_name:-$old} to $branch" HEAD "refs/heads/$branch"
                if test -n "$quiet"
                then
                        true    # nothing
                fi
        elif test -n "$detached"
        then
-               git update-ref --no-deref -m "checkout: moving to $arg" HEAD "$detached" ||
+               old_branch_name=`expr "z$oldbranch" : 'zrefs/heads/\(.*\)'`
+               git update-ref --no-deref -m "checkout: moving from ${old_branch_name:-$old} to $arg" HEAD "$detached" ||
                        die "Cannot detach HEAD"
                if test -n "$detach_warn"
                then