diff --git a/linux/build/scripts/build-inner.sh b/linux/build/scripts/build-inner.sh
index e2a11de..ef82d15 100755
--- a/linux/build/scripts/build-inner.sh
+++ b/linux/build/scripts/build-inner.sh
@@ -260,12 +260,27 @@ post_process_for_reproducibility() {
     # `--` terminates the variable-length path list of -alter_date_r;
     # without it the following -volume_date is consumed as a path and
     # xorriso bails with "Cannot find path '/-volume_date'" (run #4279).
+    # Run #4283's diagnostic decoded the residual divergence as the
+    # Rock Ridge TF (Timestamps) entry on the just-replaced
+    # /live/filesystem.squashfs node. The byte pattern was:
+    #   flags=0x0e → CREATION + MODIFICATION + ACCESS (short form)
+    #   CREATION:    `7e 05 08 00 06 2d 00`  (=SOURCE_DATE_EPOCH ✅)
+    #   MODIFICATION: A=`7e 05 08 00 18 10 00`  B=`7e 05 08 00 28 14 00`
+    #   ACCESS:      A=`7e 05 08 00 18 0f 00`  B=`7e 05 08 00 28 13 00`
+    # MODIFICATION/ACCESS each leaked the wall-clock time of -commit.
+    # So `-alter_date_r all` only fixed b (creation) on the updated
+    # node, and -update overwrote a and m at -commit.
+    #
+    # Add an explicit `-alter_date all` for /live/filesystem.squashfs
+    # AFTER -update — this way the override is the very last thing
+    # applied to that node before -commit.
     sudo --non-interactive xorriso \
         -return_with SORRY 0 \
         -indev   "${iso_file}" \
         -outdev  "${new_iso}" \
         -boot_image any keep \
         -update  "${new_sqfs}" /live/filesystem.squashfs \
+        -alter_date all "=${SOURCE_DATE_EPOCH}" /live/filesystem.squashfs -- \
         -alter_date_r all "=${SOURCE_DATE_EPOCH}" / -- \
         -volume_date c "=${SOURCE_DATE_EPOCH}" \
         -volume_date m "=${SOURCE_DATE_EPOCH}" \