diff --git a/commit-graph.c b/commit-graph.c
index 0fe3c90177..45bbea4644 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -128,16 +128,6 @@ timestamp_t commit_graph_generation(const struct commit *c)
 	return GENERATION_NUMBER_INFINITY;
 }
 
-static timestamp_t commit_graph_generation_from_graph(const struct commit *c)
-{
-	struct commit_graph_data *data =
-		commit_graph_data_slab_peek(&commit_graph_data_slab, c);
-
-	if (!data || data->graph_pos == COMMIT_NOT_FROM_GRAPH)
-		return GENERATION_NUMBER_INFINITY;
-	return data->generation;
-}
-
 static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
 {
 	unsigned int i, nth_slab;
@@ -2690,7 +2680,7 @@ static int verify_one_commit_graph(struct repository *r,
 					     oid_to_hex(&graph_parents->item->object.oid),
 					     oid_to_hex(&odb_parents->item->object.oid));
 
-			generation = commit_graph_generation_from_graph(graph_parents->item);
+			generation = commit_graph_generation(graph_parents->item);
 			if (generation > max_generation)
 				max_generation = generation;
 
@@ -2702,17 +2692,14 @@ static int verify_one_commit_graph(struct repository *r,
 			graph_report(_("commit-graph parent list for commit %s terminates early"),
 				     oid_to_hex(&cur_oid));
 
-		if (commit_graph_generation_from_graph(graph_commit)) {
-			if (generation_zero == GENERATION_ZERO_EXISTS)
-				graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
-					     oid_to_hex(&cur_oid));
-			generation_zero = GENERATION_NUMBER_EXISTS;
-		} else {
+		if (!commit_graph_generation(graph_commit)) {
 			if (generation_zero == GENERATION_NUMBER_EXISTS)
 				graph_report(_("commit-graph has generation number zero for commit %s, but non-zero elsewhere"),
 					     oid_to_hex(&cur_oid));
 			generation_zero = GENERATION_ZERO_EXISTS;
-		}
+		} else if (generation_zero == GENERATION_ZERO_EXISTS)
+			graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
+				     oid_to_hex(&cur_oid));
 
 		if (generation_zero == GENERATION_ZERO_EXISTS)
 			continue;
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 8e96471b34..4df76173a8 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -450,15 +450,14 @@ GRAPH_BYTE_FANOUT2=$(($GRAPH_FANOUT_OFFSET + 4 * 255))
 GRAPH_OID_LOOKUP_OFFSET=$(($GRAPH_FANOUT_OFFSET + 4 * 256))
 GRAPH_BYTE_OID_LOOKUP_ORDER=$(($GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN * 8))
 GRAPH_BYTE_OID_LOOKUP_MISSING=$(($GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN * 4 + 10))
-GRAPH_COMMIT_DATA_WIDTH=$(($HASH_LEN + 16))
 GRAPH_COMMIT_DATA_OFFSET=$(($GRAPH_OID_LOOKUP_OFFSET + $HASH_LEN * $NUM_COMMITS))
 GRAPH_BYTE_COMMIT_TREE=$GRAPH_COMMIT_DATA_OFFSET
 GRAPH_BYTE_COMMIT_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN))
 GRAPH_BYTE_COMMIT_EXTRA_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 4))
 GRAPH_BYTE_COMMIT_WRONG_PARENT=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 3))
 GRAPH_BYTE_COMMIT_GENERATION=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 11))
-GRAPH_BYTE_COMMIT_GENERATION_LAST=$(($GRAPH_BYTE_COMMIT_GENERATION + $(($NUM_COMMITS - 1)) * $GRAPH_COMMIT_DATA_WIDTH))
 GRAPH_BYTE_COMMIT_DATE=$(($GRAPH_COMMIT_DATA_OFFSET + $HASH_LEN + 12))
+GRAPH_COMMIT_DATA_WIDTH=$(($HASH_LEN + 16))
 GRAPH_OCTOPUS_DATA_OFFSET=$(($GRAPH_COMMIT_DATA_OFFSET + \
 			     $GRAPH_COMMIT_DATA_WIDTH * $NUM_COMMITS))
 GRAPH_BYTE_OCTOPUS=$(($GRAPH_OCTOPUS_DATA_OFFSET + 4))
@@ -597,6 +596,11 @@ test_expect_success 'detect incorrect generation number' '
 		"generation for commit"
 '
 
+test_expect_success 'detect incorrect generation number' '
+	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\01" \
+		"commit-graph generation for commit"
+'
+
 test_expect_success 'detect incorrect commit date' '
 	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_DATE "\01" \
 		"commit date"
@@ -618,16 +622,6 @@ test_expect_success 'detect incorrect chunk count' '
 		$GRAPH_CHUNK_LOOKUP_OFFSET
 '
 
-test_expect_success 'detect mixed generation numbers (non-zero to zero)' '
-	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION_LAST "\0\0\0\0" \
-		"but non-zero elsewhere"
-'
-
-test_expect_success 'detect mixed generation numbers (zero to non-zero)' '
-	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_GENERATION "\0\0\0\0" \
-		"but zero elsewhere"
-'
-
 test_expect_success 'git fsck (checks commit-graph when config set to true)' '
 	git -C full fsck &&
 	corrupt_graph_and_verify $GRAPH_BYTE_FOOTER "\00" \