diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 0bbc02e5ad7..9f0d9e7879f 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -609,6 +609,9 @@ pg_relation_filepath(PG_FUNCTION_ARGS)
 		default:
 			/* no storage, return NULL */
 			rnode.relNode = InvalidOid;
+			/* some compilers generate warnings without these next two lines */
+			rnode.dbNode = InvalidOid;
+			rnode.spcNode = InvalidOid;
 			break;
 	}