diff --git a/commit-graph.c b/commit-graph.c
index 172e679db1..3c5a2010be 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1487,7 +1487,7 @@ static void compute_reachable_generation_numbers(
 		timestamp_t gen;
 		repo_parse_commit(info->r, c);
 		gen = info->get_generation(c, info->data);
-		display_progress(info->progress, info->progress_cnt + 1);
+		display_progress(info->progress, ++info->progress_cnt);
 
 		if (gen != GENERATION_NUMBER_ZERO && gen != GENERATION_NUMBER_INFINITY)
 			continue;
diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
index d9acb63951..a85f6d685c 100755
--- a/t/t6500-gc.sh
+++ b/t/t6500-gc.sh
@@ -174,7 +174,7 @@ test_expect_success TTY 'with TTY: gc --no-quiet' '
 		git -c gc.writeCommitGraph=true gc --no-quiet >stdout 2>stderr &&
 	test_must_be_empty stdout &&
 	test_i18ngrep "Enumerating objects" stderr &&
-	test_i18ngrep "Computing commit graph generation numbers" stderr
+	test_i18ngrep "Computing commit graph generation numbers: 100% (4/4), done." stderr
 '
 
 test_expect_success 'gc --quiet' '