diff --git a/packfile.c b/packfile.c
index 9ef27508f2..e69012e7f2 100644
--- a/packfile.c
+++ b/packfile.c
@@ -923,6 +923,7 @@ unsigned long repo_approximate_object_count(struct repository *r)
 			count += p->num_objects;
 		}
 		r->objects->approximate_object_count = count;
+		r->objects->approximate_object_count_valid = 1;
 	}
 	return r->objects->approximate_object_count;
 }
diff --git a/t/perf/p5303-many-packs.sh b/t/perf/p5303-many-packs.sh
index 7ee791669a..f4c2ab0584 100755
--- a/t/perf/p5303-many-packs.sh
+++ b/t/perf/p5303-many-packs.sh
@@ -73,6 +73,10 @@ do
 		git rev-list --objects --all >/dev/null
 	'
 
+	test_perf "abbrev-commit ($nr_packs)" '
+		git rev-list --abbrev-commit HEAD >/dev/null
+	'
+
 	# This simulates the interesting part of the repack, which is the
 	# actual pack generation, without smudging the on-disk setup
 	# between trials.