diff --git a/src/custom_types.c b/src/custom_types.c
index 19171d71..62a8548f 100644
--- a/src/custom_types.c
+++ b/src/custom_types.c
@@ -344,10 +344,13 @@ chfdw_check_for_ordered_aggregate(Aggref* agg) {
     }
 
     /* Accept all ordered aggregates defined by pg_clickhouse. */
-    Oid extoid    = getExtensionOfObject(ProcedureRelationId, agg->aggfnoid);
-    char* extname = get_extension_name(extoid);
+    Oid extoid = getExtensionOfObject(ProcedureRelationId, agg->aggfnoid);
 
-    return STR_EQUAL(extname, "pg_clickhouse");
+    if (!OidIsValid(extoid)) {
+        return false;
+    }
+
+    return get_extension_oid("pg_clickhouse", true) == extoid;
 }
 
 /*
diff --git a/test/expected/functions.out b/test/expected/functions.out
index 61e1d39c..6e126b29 100644
--- a/test/expected/functions.out
+++ b/test/expected/functions.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_0.out b/test/expected/functions_0.out
index 05f94594..c3926614 100644
--- a/test/expected/functions_0.out
+++ b/test/expected/functions_0.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_1.out b/test/expected/functions_1.out
index 733a6474..65510563 100644
--- a/test/expected/functions_1.out
+++ b/test/expected/functions_1.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_2.out b/test/expected/functions_2.out
index 89433525..6637a97e 100644
--- a/test/expected/functions_2.out
+++ b/test/expected/functions_2.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_3.out b/test/expected/functions_3.out
index 8a0a802c..2783940e 100644
--- a/test/expected/functions_3.out
+++ b/test/expected/functions_3.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_4.out b/test/expected/functions_4.out
index 15b9f691..a14fe927 100644
--- a/test/expected/functions_4.out
+++ b/test/expected/functions_4.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_5.out b/test/expected/functions_5.out
index 283a2d82..6c576012 100644
--- a/test/expected/functions_5.out
+++ b/test/expected/functions_5.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_6.out b/test/expected/functions_6.out
index a3095973..2a0110b1 100644
--- a/test/expected/functions_6.out
+++ b/test/expected/functions_6.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_7.out b/test/expected/functions_7.out
index d4ab979b..5749f386 100644
--- a/test/expected/functions_7.out
+++ b/test/expected/functions_7.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_8.out b/test/expected/functions_8.out
index 82b41789..47f3315b 100644
--- a/test/expected/functions_8.out
+++ b/test/expected/functions_8.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/expected/functions_9.out b/test/expected/functions_9.out
index b2de027e..069e9686 100644
--- a/test/expected/functions_9.out
+++ b/test/expected/functions_9.out
@@ -801,6 +801,35 @@ SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LA
  {2,2,2}
 (1 row)
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Aggregate
+   Output: local_ordered_count() WITHIN GROUP (ORDER BY a)
+   ->  Foreign Scan on public.t1
+         Output: a, b, c
+         Remote SQL: SELECT a FROM functions_test.t1
+(5 rows)
+
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+ local_ordered_count 
+---------------------
+                   4
+(1 row)
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
                                                                                        QUERY PLAN                                                                                        
 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/test/sql/functions.sql b/test/sql/functions.sql
index 74b467b7..4cdc1bae 100644
--- a/test/sql/functions.sql
+++ b/test/sql/functions.sql
@@ -220,6 +220,25 @@ EXPLAIN (VERBOSE, COSTS OFF) SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITH
 SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a) FILTER (WHERE b = 1) FROM t1;
 SELECT percentile_disc(ARRAY[0.25, 0.5, 0.75]) WITHIN GROUP (ORDER BY a NULLS LAST) FROM t1;
 
+CREATE FUNCTION local_ordered_sfunc(integer, integer)
+RETURNS integer
+LANGUAGE SQL
+IMMUTABLE
+AS 'SELECT $1 + 1';
+
+CREATE AGGREGATE local_ordered_count(ORDER BY integer) (
+    SFUNC = local_ordered_sfunc,
+    STYPE = integer,
+    INITCOND = '0'
+);
+
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+SELECT local_ordered_count() WITHIN GROUP (ORDER BY a) FROM t1;
+
+DROP AGGREGATE local_ordered_count(integer);
+DROP FUNCTION local_ordered_sfunc(integer, integer);
+
 EXPLAIN (VERBOSE, COSTS OFF) SELECT date_trunc('dAy', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;
 SELECT date_trunc('day', c at time zone 'UTC') as d1 FROM t1 GROUP BY d1 ORDER BY d1;