diff --git a/builtin/repack.c b/builtin/repack.c
index 5d06872d77..8faf7ce2ef 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -457,6 +457,28 @@ int cmd_repack(int argc,
 	existing.repo = repo;
 	existing_packs_collect(&existing, &keep_pack_list);
 
+	/*
+	 * Tell pack-objects which packs we may delete. pack-objects looks
+	 * for ".keep" files on its own, and one that appears on such a
+	 * pack from now on must not make it leave out objects that would
+	 * then be deleted with the pack.
+	 */
+	if (delete_redundant &&
+	    ((pack_everything & ALL_INTO_ONE) || geometry.split_factor) &&
+	    existing_packs_has_non_kept(&existing)) {
+		struct strbuf path = STRBUF_INIT;
+		struct tempfile *non_kept_packs;
+
+		strbuf_addf(&path, "%s/tmp_non_kept_packs_XXXXXX",
+			    repo_get_object_directory(repo));
+
+		non_kept_packs = xmks_tempfile(path.buf);
+		existing_packs_write_non_kept(&existing, non_kept_packs);
+		po_args.ignore_pack_keep_from = get_tempfile_path(non_kept_packs);
+
+		strbuf_release(&path);
+	}
+
 	if (geometry.split_factor) {
 		if (pack_everything)
 			die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
@@ -644,6 +666,7 @@ int cmd_repack(int argc,
 		cruft_po_args.quiet = po_args.quiet;
 		cruft_po_args.delta_base_offset = po_args.delta_base_offset;
 		cruft_po_args.pack_kept_objects = 0;
+		cruft_po_args.ignore_pack_keep_from = po_args.ignore_pack_keep_from;
 
 		ret = write_cruft_pack(&opts, cruft_expiration,
 				       combine_cruft_below_size, &names,
diff --git a/repack.c b/repack.c
index 4c6d1f507d..e81d9b0de3 100644
--- a/repack.c
+++ b/repack.c
@@ -40,6 +40,9 @@ void prepare_pack_objects(struct child_process *cmd,
 		strvec_push(&cmd->args,  "--delta-base-offset");
 	if (!args->pack_kept_objects)
 		strvec_push(&cmd->args,  "--honor-pack-keep");
+	if (args->ignore_pack_keep_from)
+		strvec_pushf(&cmd->args, "--ignore-pack-keep-from=%s",
+			     args->ignore_pack_keep_from);
 	strvec_push(&cmd->args, out);
 	cmd->git_cmd = 1;
 	cmd->out = -1;
@@ -172,6 +175,29 @@ int existing_packs_has_non_kept(const struct existing_packs *existing)
 	return existing->non_kept_packs.nr || existing->cruft_packs.nr;
 }
 
+void existing_packs_write_non_kept(const struct existing_packs *existing,
+				   struct tempfile *f)
+{
+	struct string_list_item *item;
+	FILE *out = fdopen_tempfile(f, "w");
+
+	if (!out)
+		die(_("could not open tempfile %s for writing"),
+		    get_tempfile_path(f));
+
+	for_each_string_list_item(item, &existing->non_kept_packs)
+		fprintf(out, "%s.pack\n", item->string);
+	for_each_string_list_item(item, &existing->cruft_packs)
+		fprintf(out, "%s.pack\n", item->string);
+
+	if (close_tempfile_gently(f)) {
+		int save_errno = errno;
+		delete_tempfile(&f);
+		errno = save_errno;
+		die_errno(_("could not close non-kept packs tempfile"));
+	}
+}
+
 static void existing_pack_mark_for_deletion(struct string_list_item *item)
 {
 	item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
diff --git a/repack.h b/repack.h
index 61e554e4ed..e3bc840b9a 100644
--- a/repack.h
+++ b/repack.h
@@ -19,6 +19,11 @@ struct pack_objects_args {
 	int path_walk;
 	int delta_base_offset;
 	int pack_kept_objects;
+	/*
+	 * A file naming the packs this repack may delete, for
+	 * pack-objects' "--ignore-pack-keep-from"; the path is borrowed.
+	 */
+	const char *ignore_pack_keep_from;
 	struct list_objects_filter_options filter_options;
 };
 
@@ -28,6 +33,7 @@ struct pack_objects_args {
 }
 
 struct child_process;
+struct tempfile;
 
 void prepare_pack_objects(struct child_process *cmd,
 			  const struct pack_objects_args *args,
@@ -80,6 +86,12 @@ struct existing_packs {
 void existing_packs_collect(struct existing_packs *existing,
 			    const struct string_list *extra_keep);
 int existing_packs_has_non_kept(const struct existing_packs *existing);
+/*
+ * Write the names of the non-kept and cruft packs, the ones a repack may
+ * delete, to "f", one per line, for pack-objects' "--ignore-pack-keep-from".
+ */
+void existing_packs_write_non_kept(const struct existing_packs *existing,
+				   struct tempfile *f);
 int existing_pack_is_marked_for_deletion(struct string_list_item *item);
 void existing_packs_retain_cruft(struct existing_packs *existing,
 				 struct packed_git *cruft);
@@ -138,8 +150,6 @@ void pack_geometry_remove_redundant(struct pack_geometry *geometry,
 				    bool wrote_incremental_midx);
 void pack_geometry_release(struct pack_geometry *geometry);
 
-struct tempfile;
-
 enum repack_write_midx_mode {
 	REPACK_WRITE_MIDX_NONE,
 	REPACK_WRITE_MIDX_DEFAULT,
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 00fe259767..79fa3189f6 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -941,4 +941,53 @@ test_expect_success 'pending objects are repacked appropriately' '
 	)
 '
 
+# Put a reachable commit and an unreachable one into a single pack X in a
+# new repository "keep-race", run "git repack" with the given options and
+# have a ".keep" appear on X as pack-objects starts, i.e. after the repack
+# has decided to delete X. The unreachable commit is saved in the file
+# "keep-race/unreachable".
+keep_race_repack () {
+	git init keep-race &&
+	(
+		cd keep-race &&
+		test_commit base &&
+		git commit-tree -m unreachable HEAD^{tree} >unreachable &&
+
+		git rev-list --objects --all $(cat unreachable) >objects &&
+		X=$(git pack-objects .git/objects/pack/pack <objects) &&
+		git prune-packed &&
+
+		mkdir shim &&
+		write_script shim/git <<-EOF &&
+		test "\$1" = "pack-objects" &&
+		>"$(pwd)/.git/objects/pack/pack-$X.keep" &&
+		>"$(pwd)/keep-created"
+		GIT_EXEC_PATH="$GIT_EXEC_PATH" exec "$GIT_EXEC_PATH/git" "\$@"
+		EOF
+
+		git --exec-path="$(pwd)/shim" repack "$@" &&
+		test_path_is_file keep-created &&
+		test_path_is_missing .git/objects/pack/pack-$X.pack &&
+		git fsck
+	)
+}
+
+for args in "-a -d" "-a -d --filter=blob:none"
+do
+	test_expect_success "a .keep that shows up mid-repack loses nothing: $args" '
+		test_when_finished "rm -fr keep-race" &&
+		keep_race_repack $args
+	'
+done
+
+for args in "-A -d" "-A -d --pack-kept-objects" "-a -k -d" "--cruft -d" \
+	    "--cruft --cruft-expiration=1.week.ago -d"
+do
+	test_expect_success "a .keep that shows up mid-repack loses nothing: $args" '
+		test_when_finished "rm -fr keep-race" &&
+		keep_race_repack $args &&
+		git -C keep-race cat-file -e $(cat keep-race/unreachable)
+	'
+done
+
 test_done
diff --git a/t/t7703-repack-geometric.sh b/t/t7703-repack-geometric.sh
index f3a0650cfe..7a5e3b9ada 100755
--- a/t/t7703-repack-geometric.sh
+++ b/t/t7703-repack-geometric.sh
@@ -541,4 +541,43 @@ test_expect_success 'geometric repack works with promisor packs' '
 	)
 '
 
+test_expect_success 'a ".keep" that shows up mid-repack does not lose objects' '
+	test_when_finished "rm -fr race" &&
+	git init race &&
+	(
+		cd race &&
+
+		test_commit kept &&
+		test_commit pack &&
+
+		KEPT=$(git pack-objects --revs $packdir/pack <<-EOF
+		refs/tags/kept
+		EOF
+		) &&
+		git pack-objects --revs $packdir/pack <<-EOF &&
+		refs/tags/pack
+		^refs/tags/kept
+		EOF
+		git prune-packed &&
+
+		# Neither pack is twice the size of the other, so both are
+		# rolled up and deleted. Have a ".keep" appear on one of them
+		# as pack-objects starts, after the repack has decided to
+		# delete it; its objects must still end up in the new pack.
+		mkdir shim &&
+		write_script shim/git <<-EOF &&
+		test "\$1" = "pack-objects" &&
+		>"$(pwd)/$packdir/pack-$KEPT.keep" &&
+		>"$(pwd)/keep-created"
+		GIT_EXEC_PATH="$GIT_EXEC_PATH" exec "$GIT_EXEC_PATH/git" "\$@"
+		EOF
+
+		git --exec-path="$(pwd)/shim" repack --geometric 2 -d &&
+		test_path_is_file keep-created &&
+		test_path_is_missing $packdir/pack-$KEPT.pack &&
+
+		git fsck
+	)
+'
+
 test_done