diff --git a/src/test/regress/expected/polymorphism.out b/src/test/regress/expected/polymorphism.out
index 1ff40764d9..236b2532b3 100644
--- a/src/test/regress/expected/polymorphism.out
+++ b/src/test/regress/expected/polymorphism.out
@@ -786,6 +786,8 @@ create aggregate build_group(int8, integer) (
   STYPE = int8[]
 );
 -- check proper resolution of data types for polymorphic transfn/finalfn
+create function first_el_transfn(anyarray, anyelement) returns anyarray as
+'select $1 || $2' language sql immutable;
 create function first_el(anyarray) returns anyelement as
 'select $1[1]' language sql strict immutable;
 create aggregate first_el_agg_f8(float8) (
@@ -794,7 +796,7 @@ create aggregate first_el_agg_f8(float8) (
   FINALFUNC = first_el
 );
 create aggregate first_el_agg_any(anyelement) (
-  SFUNC = array_append,
+  SFUNC = first_el_transfn,
   STYPE = anyarray,
   FINALFUNC = first_el
 );
diff --git a/src/test/regress/sql/polymorphism.sql b/src/test/regress/sql/polymorphism.sql
index e5222f1f81..d2e302c330 100644
--- a/src/test/regress/sql/polymorphism.sql
+++ b/src/test/regress/sql/polymorphism.sql
@@ -549,6 +549,9 @@ create aggregate build_group(int8, integer) (
 
 -- check proper resolution of data types for polymorphic transfn/finalfn
 
+create function first_el_transfn(anyarray, anyelement) returns anyarray as
+'select $1 || $2' language sql immutable;
+
 create function first_el(anyarray) returns anyelement as
 'select $1[1]' language sql strict immutable;
 
@@ -559,7 +562,7 @@ create aggregate first_el_agg_f8(float8) (
 );
 
 create aggregate first_el_agg_any(anyelement) (
-  SFUNC = array_append,
+  SFUNC = first_el_transfn,
   STYPE = anyarray,
   FINALFUNC = first_el
 );