diff --git a/src/backend/executor/nodeCtescan.c b/src/backend/executor/nodeCtescan.c
index 3c2f684..64248cb 100644
--- a/src/backend/executor/nodeCtescan.c
+++ b/src/backend/executor/nodeCtescan.c
@@ -53,8 +53,21 @@ CteScanNext(CteScanState *node)
 	 */
 	eof_tuplestore = tuplestore_ateof(tuplestorestate);
 
+	/*
+	 * Before fetching, we need to handle a special case: when reversing
+	 * direction at the end of the tuplestore, the next
+	 * tuplestore_gettupleslot() call will return the last tuple. But since
+	 * that tuple was just seen, we want to move past it. This is necessary
+	 * because the tuplestore get routines always move the current pointer,
+	 * unless they hit the end (or beginning) of the store.
+	 */
 	if (!forward && eof_tuplestore)
 	{
+		/*
+		 * However, once we hit the end of the underlying node any call while
+		 * at the end of the tuplestore will return NULL. In that case, we DO
+		 * want to return the last row in the tuplestore.
+		 */
 		if (!node->leader->eof_cte)
 		{
 			/*
diff --git a/src/backend/executor/nodeMaterial.c b/src/backend/executor/nodeMaterial.c
index 9ab03f3..197b91b 100644
--- a/src/backend/executor/nodeMaterial.c
+++ b/src/backend/executor/nodeMaterial.c
@@ -82,16 +82,23 @@ ExecMaterial(MaterialState *node)
 	eof_tuplestore = (tuplestorestate == NULL) ||
 		tuplestore_ateof(tuplestorestate);
 
+	/*
+	 * Before fetching, we need to handle a special case: when reversing
+	 * direction at the end of the tuplestore, the next
+	 * tuplestore_gettupleslot() call will return the last tuple. But since
+	 * that tuple was just seen, we want to move past it. This is necessary
+	 * because the tuplestore get routines always move the current pointer,
+	 * unless they hit the end (or beginning) of the store.
+	 */
 	if (!forward && eof_tuplestore)
 	{
+		/*
+		 * However, once we hit the end of the underlying node any call while
+		 * at the end of the tuplestore will return NULL. In that case, we DO
+		 * want to return the last row in the tuplestore.
+		 */
 		if (!node->eof_underlying)
 		{
-			/*
-			 * When reversing direction at tuplestore EOF, the first
-			 * gettupleslot call will fetch the last-added tuple; but we want
-			 * to return the one before that, if possible. So do an extra
-			 * fetch.
-			 */
 			if (!tuplestore_advance(tuplestorestate, forward))
 				return NULL;	/* the tuplestore must be empty */
 		}