diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 17c42d4a88..967604b8a5 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -999,6 +999,8 @@ typedef TupleTableSlot *(*ExecProcNodeMtd) (struct PlanState *pstate);
  */
 typedef struct PlanState
 {
+	pg_node_attr(abstract)
+
 	NodeTag		type;
 
 	Plan	   *plan;			/* associated Plan node */
diff --git a/src/include/nodes/memnodes.h b/src/include/nodes/memnodes.h
index bbbe151e39..16cd56da6d 100644
--- a/src/include/nodes/memnodes.h
+++ b/src/include/nodes/memnodes.h
@@ -77,6 +77,8 @@ typedef struct MemoryContextMethods
 
 typedef struct MemoryContextData
 {
+	pg_node_attr(abstract)		/* there are no nodes of this type */
+
 	NodeTag		type;			/* identifies exact kind of context */
 	/* these two fields are placed here to minimize alignment wastage: */
 	bool		isReset;		/* T = no space alloced since last reset */
diff --git a/src/test/modules/test_oat_hooks/test_oat_hooks.c b/src/test/modules/test_oat_hooks/test_oat_hooks.c
index b648ee67ff..c9869b21fd 100644
--- a/src/test/modules/test_oat_hooks/test_oat_hooks.c
+++ b/src/test/modules/test_oat_hooks/test_oat_hooks.c
@@ -618,9 +618,6 @@ nodetag_to_string(NodeTag tag)
 		case T_PlanInvalItem:
 			return "PlanInvalItem";
 			break;
-		case T_PlanState:
-			return "PlanState";
-			break;
 		case T_ResultState:
 			return "ResultState";
 			break;