diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index 1686cbdb06..93a6f18c49 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -76,9 +76,12 @@ under /root/.guix-profile where GUIX is installed."
           (with-directory-excursion %root
             (zero? (system* "tar" "--xz" "--format=gnu"
 
-                            ;; avoid non-determinism in the archive
+                            ;; Avoid non-determinism in the archive.  Use
+                            ;; mtime = 1, not zero, because that is what the
+                            ;; daemon does for files in the store (see the
+                            ;; 'mtimeStore' constant in local-store.cc.)
                             "--sort=name"
-                            "--mtime=@0"          ;for files in /var/guix
+                            "--mtime=@1"          ;for files in /var/guix
                             "--owner=root:0"
                             "--group=root:0"