diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 6fcfd031428..6b616fbd6fc 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -1122,3 +1122,19 @@ any_value_transfn(PG_FUNCTION_ARGS)
 {
 	PG_RETURN_DATUM(PG_GETARG_DATUM(0));
 }
+
+/*
+ * nonnull()
+ *	Ensure that the argument is not NULL
+ *	If NULL, raise an error; otherwise return the value unchanged
+ */
+Datum
+nonnull(PG_FUNCTION_ARGS)
+{
+	if (PG_ARGISNULL(0))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("null value not allowed")));
+
+	PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..fa4797da00b 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -12518,6 +12518,9 @@
 { oid => '6292', descr => 'aggregate transition function',
   proname => 'any_value_transfn', prorettype => 'anyelement',
   proargtypes => 'anyelement anyelement', prosrc => 'any_value_transfn' },
+{ oid => '6', descr => 'ensure value is not null',
+  proname => 'nonnull', proisstrict => 'f', prorettype => 'anyelement',
+  proargtypes => 'anyelement', prosrc => 'nonnull' },
 
 { oid => '6321', descr => 'list of available WAL summary files',
   proname => 'pg_available_wal_summaries', prorows => '100', proretset => 't',