diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index 681a2eb25a9..3defcb3b886 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -387,7 +387,10 @@ process_equivalence(PlannerInfo *root,
 		 */
 		ec1->ec_members = list_concat(ec1->ec_members, ec2->ec_members);
 		ec1->ec_sources = list_concat(ec1->ec_sources, ec2->ec_sources);
-		/* Updates ec1's ec_derives_list and ec_derives_hash if present. */
+		/*
+		 * Merges ec2's ec_derives_list and ec_derives_hash, if present, into
+		 * those of ec1.
+		 */
 		ec_add_derived_clauses(ec1, ec2->ec_derives_list);
 		ec1->ec_relids = bms_join(ec1->ec_relids, ec2->ec_relids);
 		ec1->ec_has_const |= ec2->ec_has_const;
@@ -3513,7 +3516,7 @@ add_clause_to_ec_derives_hash(EquivalenceClass *ec, RestrictInfo *rinfo)
 	if (rinfo->right_em->em_is_const)
 	{
 		/*
-		 * Clauses containing a constant never considered redundant, so
+		 * Clauses containing a constant are never considered redundant, so
 		 * parent_ec is not set.
 		 */
 		Assert(!rinfo->parent_ec);