diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index 9dafaef7aaf..14df9d8b673 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -1016,8 +1016,8 @@ hg binary."
          (not (vc-hg--requirements-understood-p repo))
          ;; Dirstate too small to be valid
          (< (nth 7 dirstate-attr) 40)
-         ;; We want to store 32-bit unsigned values in fixnums
-         (< most-positive-fixnum 4294967295)
+         ;; We want to store 32-bit unsigned values in fixnums.
+         (zerop (lsh -1 32))
          (progn
            (setf repo-relative-filename
                  (file-relative-name truename repo))