diff --git a/midx-write.c b/midx-write.c
index b262631ae4..55342fcb6d 100644
--- a/midx-write.c
+++ b/midx-write.c
@@ -410,11 +410,6 @@ static int write_midx_pack_names(struct hashfile *f, void *data)
 		if (ctx->info[i].expired)
 			continue;
 
-		if (i && strcmp(ctx->info[i].pack_name, ctx->info[i - 1].pack_name) <= 0)
-			BUG("incorrect pack-file order: %s before %s",
-			    ctx->info[i - 1].pack_name,
-			    ctx->info[i].pack_name);
-
 		writelen = strlen(ctx->info[i].pack_name) + 1;
 		hashwrite(f, ctx->info[i].pack_name, writelen);
 		written += writelen;
diff --git a/midx.c b/midx.c
index f9b11de9ca..4d5fe88064 100644
--- a/midx.c
+++ b/midx.c
@@ -209,11 +209,6 @@ static struct multi_pack_index *load_multi_pack_index_one(struct odb_source *sou
 		if (!end)
 			die(_("multi-pack-index pack-name chunk is too short"));
 		cur_pack_name = end + 1;
-
-		if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0)
-			die(_("multi-pack-index pack names out of order: '%s' before '%s'"),
-			      m->pack_names[i - 1],
-			      m->pack_names[i]);
 	}
 
 	trace2_data_intmax("midx", r, "load/num_packs", m->num_packs);
@@ -411,6 +406,7 @@ void close_midx(struct multi_pack_index *m)
 	}
 	FREE_AND_NULL(m->packs);
 	FREE_AND_NULL(m->pack_names);
+	FREE_AND_NULL(m->pack_names_sorted);
 	free(m);
 }
 
@@ -656,17 +652,37 @@ int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 	return strcmp(idx_or_pack_name, idx_name);
 }
 
+
+static int midx_pack_names_cmp(const void *a, const void *b, void *m_)
+{
+	struct multi_pack_index *m = m_;
+	return strcmp(m->pack_names[*(const size_t *)a],
+		      m->pack_names[*(const size_t *)b]);
+}
+
 static int midx_contains_pack_1(struct multi_pack_index *m,
 				const char *idx_or_pack_name)
 {
 	uint32_t first = 0, last = m->num_packs;
 
+	if (!m->pack_names_sorted) {
+		uint32_t i;
+
+		ALLOC_ARRAY(m->pack_names_sorted, m->num_packs);
+
+		for (i = 0; i < m->num_packs; i++)
+			m->pack_names_sorted[i] = i;
+
+		QSORT_S(m->pack_names_sorted, m->num_packs, midx_pack_names_cmp,
+			m);
+	}
+
 	while (first < last) {
 		uint32_t mid = first + (last - first) / 2;
 		const char *current;
 		int cmp;
 
-		current = m->pack_names[mid];
+		current = m->pack_names[m->pack_names_sorted[mid]];
 		cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
 		if (!cmp)
 			return 1;
diff --git a/midx.h b/midx.h
index e188ffeb57..39bf04b18e 100644
--- a/midx.h
+++ b/midx.h
@@ -71,6 +71,7 @@ struct multi_pack_index {
 	uint32_t num_packs_in_base;
 
 	const char **pack_names;
+	size_t *pack_names_sorted;
 	struct packed_git **packs;
 };
 
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index ca020091dd..03676d37b9 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -450,11 +450,6 @@ test_expect_success 'verify invalid chunk offset' '
 		"improper chunk offset(s)"
 '
 
-test_expect_success 'verify packnames out of order' '
-	corrupt_midx_and_verify $MIDX_BYTE_PACKNAME_ORDER "z" $objdir \
-		"pack names out of order"
-'
-
 test_expect_success 'verify missing pack' '
 	corrupt_midx_and_verify $MIDX_BYTE_PACKNAME_ORDER "a" $objdir \
 		"failed to load pack"