diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index c88389df24..f5e66e9969 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -69,10 +69,12 @@ static int graph_verify(int argc, const char **argv, const char *prefix)
 	struct commit_graph *graph = NULL;
 	struct object_directory *odb = NULL;
 	char *graph_name;
-	int open_ok;
+	char *chain_name;
+	enum { OPENED_NONE, OPENED_GRAPH, OPENED_CHAIN } opened = OPENED_NONE;
 	int fd;
 	struct stat st;
 	int flags = 0;
+	int incomplete_chain = 0;
 	int ret;
 
 	static struct option builtin_commit_graph_verify_options[] = {
@@ -102,24 +104,39 @@ static int graph_verify(int argc, const char **argv, const char *prefix)
 
 	odb = find_odb(the_repository, opts.obj_dir);
 	graph_name = get_commit_graph_filename(odb);
-	open_ok = open_commit_graph(graph_name, &fd, &st);
-	if (!open_ok && errno != ENOENT)
+	chain_name = get_commit_graph_chain_filename(odb);
+	if (open_commit_graph(graph_name, &fd, &st))
+		opened = OPENED_GRAPH;
+	else if (errno != ENOENT)
 		die_errno(_("Could not open commit-graph '%s'"), graph_name);
+	else if (open_commit_graph_chain(chain_name, &fd, &st))
+		opened = OPENED_CHAIN;
+	else if (errno != ENOENT)
+		die_errno(_("could not open commit-graph chain '%s'"), chain_name);
 
 	FREE_AND_NULL(graph_name);
+	FREE_AND_NULL(chain_name);
 	FREE_AND_NULL(options);
 
-	if (open_ok)
+	if (opened == OPENED_NONE)
+		return 0;
+	else if (opened == OPENED_GRAPH)
 		graph = load_commit_graph_one_fd_st(the_repository, fd, &st, odb);
 	else
-		graph = read_commit_graph_one(the_repository, odb);
+		graph = load_commit_graph_chain_fd_st(the_repository, fd, &st,
+						      &incomplete_chain);
 
-	/* Return failure if open_ok predicted success */
 	if (!graph)
-		return !!open_ok;
+		return 1;
 
 	ret = verify_commit_graph(the_repository, graph, flags);
 	free_commit_graph(graph);
+
+	if (incomplete_chain) {
+		error("one or more commit-graph chain files could not be loaded");
+		ret |= 1;
+	}
+
 	return ret;
 }
 
diff --git a/commit-graph.c b/commit-graph.c
index 5e8a3a5085..1a56efcf69 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -473,6 +473,31 @@ static struct commit_graph *load_commit_graph_v1(struct repository *r,
 	return g;
 }
 
+/*
+ * returns 1 if and only if all graphs in the chain have
+ * corrected commit dates stored in the generation_data chunk.
+ */
+static int validate_mixed_generation_chain(struct commit_graph *g)
+{
+	int read_generation_data = 1;
+	struct commit_graph *p = g;
+
+	while (read_generation_data && p) {
+		read_generation_data = p->read_generation_data;
+		p = p->base_graph;
+	}
+
+	if (read_generation_data)
+		return 1;
+
+	while (g) {
+		g->read_generation_data = 0;
+		g = g->base_graph;
+	}
+
+	return 0;
+}
+
 static int add_graph_to_chain(struct commit_graph *g,
 			      struct commit_graph *chain,
 			      struct object_id *oids,
@@ -513,31 +538,41 @@ static int add_graph_to_chain(struct commit_graph *g,
 	return 1;
 }
 
-static struct commit_graph *load_commit_graph_chain(struct repository *r,
-						    struct object_directory *odb)
+int open_commit_graph_chain(const char *chain_file,
+			    int *fd, struct stat *st)
+{
+	*fd = git_open(chain_file);
+	if (*fd < 0)
+		return 0;
+	if (fstat(*fd, st)) {
+		close(*fd);
+		return 0;
+	}
+	if (st->st_size < the_hash_algo->hexsz) {
+		close(*fd);
+		if (!st->st_size) {
+			/* treat empty files the same as missing */
+			errno = ENOENT;
+		} else {
+			warning("commit-graph chain file too small");
+			errno = EINVAL;
+		}
+		return 0;
+	}
+	return 1;
+}
+
+struct commit_graph *load_commit_graph_chain_fd_st(struct repository *r,
+						   int fd, struct stat *st,
+						   int *incomplete_chain)
 {
 	struct commit_graph *graph_chain = NULL;
 	struct strbuf line = STRBUF_INIT;
-	struct stat st;
 	struct object_id *oids;
 	int i = 0, valid = 1, count;
-	char *chain_name = get_commit_graph_chain_filename(odb);
-	FILE *fp;
-	int stat_res;
+	FILE *fp = xfdopen(fd, "r");
 
-	fp = fopen(chain_name, "r");
-	stat_res = stat(chain_name, &st);
-	free(chain_name);
-
-	if (!fp)
-		return NULL;
-	if (stat_res ||
-	    st.st_size <= the_hash_algo->hexsz) {
-		fclose(fp);
-		return NULL;
-	}
-
-	count = st.st_size / (the_hash_algo->hexsz + 1);
+	count = st->st_size / (the_hash_algo->hexsz + 1);
 	CALLOC_ARRAY(oids, count);
 
 	prepare_alt_odb(r);
@@ -578,36 +613,32 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
 		}
 	}
 
+	validate_mixed_generation_chain(graph_chain);
+
 	free(oids);
 	fclose(fp);
 	strbuf_release(&line);
 
+	*incomplete_chain = !valid;
 	return graph_chain;
 }
 
-/*
- * returns 1 if and only if all graphs in the chain have
- * corrected commit dates stored in the generation_data chunk.
- */
-static int validate_mixed_generation_chain(struct commit_graph *g)
+static struct commit_graph *load_commit_graph_chain(struct repository *r,
+						    struct object_directory *odb)
 {
-	int read_generation_data = 1;
-	struct commit_graph *p = g;
+	char *chain_file = get_commit_graph_chain_filename(odb);
+	struct stat st;
+	int fd;
+	struct commit_graph *g = NULL;
 
-	while (read_generation_data && p) {
-		read_generation_data = p->read_generation_data;
-		p = p->base_graph;
+	if (open_commit_graph_chain(chain_file, &fd, &st)) {
+		int incomplete;
+		/* ownership of fd is taken over by load function */
+		g = load_commit_graph_chain_fd_st(r, fd, &st, &incomplete);
 	}
 
-	if (read_generation_data)
-		return 1;
-
-	while (g) {
-		g->read_generation_data = 0;
-		g = g->base_graph;
-	}
-
-	return 0;
+	free(chain_file);
+	return g;
 }
 
 struct commit_graph *read_commit_graph_one(struct repository *r,
@@ -618,8 +649,6 @@ struct commit_graph *read_commit_graph_one(struct repository *r,
 	if (!g)
 		g = load_commit_graph_chain(r, odb);
 
-	validate_mixed_generation_chain(g);
-
 	return g;
 }
 
diff --git a/commit-graph.h b/commit-graph.h
index 5e534f0fcc..20ada7e891 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -26,6 +26,7 @@ struct string_list;
 char *get_commit_graph_filename(struct object_directory *odb);
 char *get_commit_graph_chain_filename(struct object_directory *odb);
 int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
+int open_commit_graph_chain(const char *chain_file, int *fd, struct stat *st);
 
 /*
  * Given a commit struct, try to fill the commit struct info, including:
@@ -105,6 +106,9 @@ struct commit_graph {
 struct commit_graph *load_commit_graph_one_fd_st(struct repository *r,
 						 int fd, struct stat *st,
 						 struct object_directory *odb);
+struct commit_graph *load_commit_graph_chain_fd_st(struct repository *r,
+						   int fd, struct stat *st,
+						   int *incomplete_chain);
 struct commit_graph *read_commit_graph_one(struct repository *r,
 					   struct object_directory *odb);
 
diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh
index 36c4141e67..06bb897f02 100755
--- a/t/t5324-split-commit-graph.sh
+++ b/t/t5324-split-commit-graph.sh
@@ -285,6 +285,32 @@ test_expect_success 'verify hashes along chain, even in shallow' '
 	)
 '
 
+test_expect_success 'verify notices chain slice which is bogus (base)' '
+	git clone --no-hardlinks . verify-chain-bogus-base &&
+	(
+		cd verify-chain-bogus-base &&
+		git commit-graph verify &&
+		base_file=$graphdir/graph-$(sed -n 1p $graphdir/commit-graph-chain).graph &&
+		echo "garbage" >$base_file &&
+		test_must_fail git commit-graph verify 2>test_err &&
+		grep -v "^+" test_err >err &&
+		grep "commit-graph file is too small" err
+	)
+'
+
+test_expect_success 'verify notices chain slice which is bogus (tip)' '
+	git clone --no-hardlinks . verify-chain-bogus-tip &&
+	(
+		cd verify-chain-bogus-tip &&
+		git commit-graph verify &&
+		tip_file=$graphdir/graph-$(sed -n 2p $graphdir/commit-graph-chain).graph &&
+		echo "garbage" >$tip_file &&
+		test_must_fail git commit-graph verify 2>test_err &&
+		grep -v "^+" test_err >err &&
+		grep "commit-graph file is too small" err
+	)
+'
+
 test_expect_success 'verify --shallow does not check base contents' '
 	git clone --no-hardlinks . verify-shallow &&
 	(
@@ -306,27 +332,54 @@ test_expect_success 'warn on base graph chunk incorrect' '
 		git commit-graph verify &&
 		base_file=$graphdir/graph-$(tail -n 1 $graphdir/commit-graph-chain).graph &&
 		corrupt_file "$base_file" $(test_oid base) "\01" &&
-		git commit-graph verify --shallow 2>test_err &&
+		test_must_fail git commit-graph verify --shallow 2>test_err &&
 		grep -v "^+" test_err >err &&
 		test_i18ngrep "commit-graph chain does not match" err
 	)
 '
 
-test_expect_success 'verify after commit-graph-chain corruption' '
-	git clone --no-hardlinks . verify-chain &&
+test_expect_success 'verify after commit-graph-chain corruption (base)' '
+	git clone --no-hardlinks . verify-chain-base &&
 	(
-		cd verify-chain &&
-		corrupt_file "$graphdir/commit-graph-chain" 60 "G" &&
-		git commit-graph verify 2>test_err &&
+		cd verify-chain-base &&
+		corrupt_file "$graphdir/commit-graph-chain" 30 "G" &&
+		test_must_fail git commit-graph verify 2>test_err &&
 		grep -v "^+" test_err >err &&
 		test_i18ngrep "invalid commit-graph chain" err &&
-		corrupt_file "$graphdir/commit-graph-chain" 60 "A" &&
-		git commit-graph verify 2>test_err &&
+		corrupt_file "$graphdir/commit-graph-chain" 30 "A" &&
+		test_must_fail git commit-graph verify 2>test_err &&
 		grep -v "^+" test_err >err &&
 		test_i18ngrep "unable to find all commit-graph files" err
 	)
 '
 
+test_expect_success 'verify after commit-graph-chain corruption (tip)' '
+	git clone --no-hardlinks . verify-chain-tip &&
+	(
+		cd verify-chain-tip &&
+		corrupt_file "$graphdir/commit-graph-chain" 70 "G" &&
+		test_must_fail git commit-graph verify 2>test_err &&
+		grep -v "^+" test_err >err &&
+		test_i18ngrep "invalid commit-graph chain" err &&
+		corrupt_file "$graphdir/commit-graph-chain" 70 "A" &&
+		test_must_fail git commit-graph verify 2>test_err &&
+		grep -v "^+" test_err >err &&
+		test_i18ngrep "unable to find all commit-graph files" err
+	)
+'
+
+test_expect_success 'verify notices too-short chain file' '
+	git clone --no-hardlinks . verify-chain-short &&
+	(
+		cd verify-chain-short &&
+		git commit-graph verify &&
+		echo "garbage" >$graphdir/commit-graph-chain &&
+		test_must_fail git commit-graph verify 2>test_err &&
+		grep -v "^+" test_err >err &&
+		grep "commit-graph chain file too small" err
+	)
+'
+
 test_expect_success 'verify across alternates' '
 	git clone --no-hardlinks . verify-alt &&
 	(