diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 1bb25738a5..6b4022c3bc 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -6566,7 +6566,7 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (select_rte)
 	{
 		/* Add the SELECT */
-		get_query_def(select_rte->subquery, buf, NIL, NULL,
+		get_query_def(select_rte->subquery, buf, context->namespaces, NULL,
 					  context->prettyFlags, context->wrapColumn,
 					  context->indentLevel);
 	}
@@ -7919,10 +7919,12 @@ get_parameter(Param *param, deparse_context *context)
 	 * If it's an external parameter, see if the outermost namespace provides
 	 * function argument names.
 	 */
-	if (param->paramkind == PARAM_EXTERN)
+	if (param->paramkind == PARAM_EXTERN && context->namespaces != NIL)
 	{
-		dpns = lfirst(list_tail(context->namespaces));
-		if (dpns->argnames)
+		dpns = llast(context->namespaces);
+		if (dpns->argnames &&
+			param->paramid > 0 &&
+			param->paramid <= dpns->numargs)
 		{
 			char	   *argname = dpns->argnames[param->paramid - 1];
 
diff --git a/src/test/regress/expected/create_function_3.out b/src/test/regress/expected/create_function_3.out
index a77df01042..3a4fd45147 100644
--- a/src/test/regress/expected/create_function_3.out
+++ b/src/test/regress/expected/create_function_3.out
@@ -279,6 +279,13 @@ CREATE FUNCTION functest_S_13() RETURNS boolean
         SELECT 1;
         SELECT false;
     END;
+-- check display of function argments in sub-SELECT
+CREATE TABLE functest1 (i int);
+CREATE FUNCTION functest_S_16(a int, b int) RETURNS void
+    LANGUAGE SQL
+    BEGIN ATOMIC
+        INSERT INTO functest1 SELECT a + $2;
+    END;
 -- error: duplicate function body
 CREATE FUNCTION functest_S_xxx(x int) RETURNS int
     LANGUAGE SQL
@@ -417,6 +424,20 @@ SELECT pg_get_functiondef('functest_S_15'::regproc);
  
 (1 row)
 
+SELECT pg_get_functiondef('functest_S_16'::regproc);
+                              pg_get_functiondef                               
+-------------------------------------------------------------------------------
+ CREATE OR REPLACE FUNCTION temp_func_test.functest_s_16(a integer, b integer)+
+  RETURNS void                                                                +
+  LANGUAGE sql                                                                +
+ BEGIN ATOMIC                                                                 +
+  INSERT INTO functest1 (i)  SELECT (functest_s_16.a + functest_s_16.b);      +
+ END                                                                          +
+ 
+(1 row)
+
+DROP TABLE functest1 CASCADE;
+NOTICE:  drop cascades to function functest_s_16(integer,integer)
 -- test with views
 CREATE TABLE functest3 (a int);
 INSERT INTO functest3 VALUES (1), (2);
diff --git a/src/test/regress/sql/create_function_3.sql b/src/test/regress/sql/create_function_3.sql
index 23a46b0b11..7edd757b8f 100644
--- a/src/test/regress/sql/create_function_3.sql
+++ b/src/test/regress/sql/create_function_3.sql
@@ -180,6 +180,14 @@ CREATE FUNCTION functest_S_13() RETURNS boolean
         SELECT false;
     END;
 
+-- check display of function argments in sub-SELECT
+CREATE TABLE functest1 (i int);
+CREATE FUNCTION functest_S_16(a int, b int) RETURNS void
+    LANGUAGE SQL
+    BEGIN ATOMIC
+        INSERT INTO functest1 SELECT a + $2;
+    END;
+
 -- error: duplicate function body
 CREATE FUNCTION functest_S_xxx(x int) RETURNS int
     LANGUAGE SQL
@@ -217,6 +225,9 @@ SELECT pg_get_functiondef('functest_S_3a'::regproc);
 SELECT pg_get_functiondef('functest_S_10'::regproc);
 SELECT pg_get_functiondef('functest_S_13'::regproc);
 SELECT pg_get_functiondef('functest_S_15'::regproc);
+SELECT pg_get_functiondef('functest_S_16'::regproc);
+
+DROP TABLE functest1 CASCADE;
 
 -- test with views
 CREATE TABLE functest3 (a int);