diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index eb41f3bea7c..b49acb2b9ef 100644
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -74,7 +74,8 @@ $in_progress_h->query_safe(q(BEGIN; SELECT pg_current_xact_id();));
 # delete one row from table, while background transaction is in progress
 $node->safe_psql('postgres', q(DELETE FROM quebec WHERE i = 1;));
 # create index concurrently, which will skip the deleted row
-$node->safe_psql('postgres', q(CREATE INDEX CONCURRENTLY oscar ON quebec(i);));
+$node->safe_psql('postgres',
+	q(CREATE INDEX CONCURRENTLY oscar ON quebec(i);));
 
 # check index using bt_index_parent_check
 $result = $node->psql('postgres',
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 32648c6c6d0..120f02cf237 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -90,9 +90,11 @@ typedef struct BtreeCheckState
 	BufferAccessStrategy checkstrategy;
 
 	/*
-	 * Info for uniqueness checking. Fill these fields once per index check.
+	 * Info for uniqueness checking. Fill this field and the one below once
+	 * per index check.
 	 */
 	IndexInfo  *indexinfo;
+	/* Table scan snapshot for heapallindexed and checkunique */
 	Snapshot	snapshot;
 
 	/*