diff --git a/src/backend/executor/execSRF.c b/src/backend/executor/execSRF.c
index 8aec3b549b..545b6c19da 100644
--- a/src/backend/executor/execSRF.c
+++ b/src/backend/executor/execSRF.c
@@ -353,11 +353,21 @@ ExecMakeTableFunctionResult(SetExprState *setexpr,
 			 */
 			if (rsinfo.isDone != ExprMultipleResult)
 				break;
+
+			/*
+			 * Check that set-returning functions were properly declared.
+			 * (Note: for historical reasons, we don't complain if a non-SRF
+			 * returns ExprEndResult; that's treated as returning NULL.)
+			 */
+			if (!returnsSet)
+				ereport(ERROR,
+						(errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED),
+						 errmsg("table-function protocol for value-per-call mode was not followed")));
 		}
 		else if (rsinfo.returnMode == SFRM_Materialize)
 		{
 			/* check we're on the same page as the function author */
-			if (!first_time || rsinfo.isDone != ExprSingleResult)
+			if (!first_time || rsinfo.isDone != ExprSingleResult || !returnsSet)
 				ereport(ERROR,
 						(errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED),
 						 errmsg("table-function protocol for materialize mode was not followed")));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 506689d8ac..a0fe0851c4 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5287,8 +5287,9 @@
   proargnames => '{slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slots' },
 { oid => '6118', descr => 'statistics: information about subscription',
-  proname => 'pg_stat_get_subscription', proisstrict => 'f', provolatile => 's',
-  proparallel => 'r', prorettype => 'record', proargtypes => 'oid',
+  proname => 'pg_stat_get_subscription', prorows => '10', proisstrict => 'f',
+  proretset => 't', provolatile => 's', proparallel => 'r',
+  prorettype => 'record', proargtypes => 'oid',
   proallargtypes => '{oid,oid,oid,int4,pg_lsn,timestamptz,timestamptz,pg_lsn,timestamptz}',
   proargmodes => '{i,o,o,o,o,o,o,o,o}',
   proargnames => '{subid,subid,relid,pid,received_lsn,last_msg_send_time,last_msg_receipt_time,latest_end_lsn,latest_end_time}',