diff --git a/src/backend/distributed/planner/multi_logical_optimizer.c b/src/backend/distributed/planner/multi_logical_optimizer.c
index f93312779..52db3da29 100644
--- a/src/backend/distributed/planner/multi_logical_optimizer.c
+++ b/src/backend/distributed/planner/multi_logical_optimizer.c
@@ -2896,7 +2896,9 @@ GetAggregateType(Oid aggFunctionId)
 	}
 
 	aggregateCount = lengthof(AggregateNames);
-	for (aggregateIndex = 0; aggregateIndex < aggregateCount; aggregateIndex++)
+
+	Assert(AGGREGATE_INVALID_FIRST == 0);
+	for (aggregateIndex = 1; aggregateIndex < aggregateCount; aggregateIndex++)
 	{
 		const char *aggregateName = AggregateNames[aggregateIndex];
 		if (strncmp(aggregateName, aggregateProcName, NAMEDATALEN) == 0)
diff --git a/src/test/regress/expected/multi_simple_queries.out b/src/test/regress/expected/multi_simple_queries.out
index 7a158efc2..f77983520 100644
--- a/src/test/regress/expected/multi_simple_queries.out
+++ b/src/test/regress/expected/multi_simple_queries.out
@@ -544,7 +544,6 @@ COPY articles_single_shard TO stdout;
 DEBUG:  Creating router plan
 DEBUG:  Plan is router executable
 50	10	anjanette	19519
--- error out for queries with aggregates
 SELECT avg(word_count)
 	FROM articles
 	WHERE author_id = 2;
@@ -556,6 +555,16 @@ DETAIL:  distribution column value: 2
  12356.400000000000
 (1 row)
 
+-- error out on unsupported aggregate
+SET client_min_messages to 'NOTICE';
+CREATE AGGREGATE public.invalid(int) (
+    sfunc = int4pl,
+    stype = int
+);
+SELECT invalid(word_count) FROM articles;
+ERROR:  unsupported aggregate function invalid
+DROP AGGREGATE invalid(int);
+SET client_min_messages to 'DEBUG2';
 -- max, min, sum, count is somehow implemented
 -- differently in distributed planning 
 SELECT max(word_count) as max, min(word_count) as min,
diff --git a/src/test/regress/expected/multi_simple_queries_0.out b/src/test/regress/expected/multi_simple_queries_0.out
index 5e5329b4e..cd11339c2 100644
--- a/src/test/regress/expected/multi_simple_queries_0.out
+++ b/src/test/regress/expected/multi_simple_queries_0.out
@@ -488,7 +488,6 @@ COPY articles_single_shard TO stdout;
 DEBUG:  Creating router plan
 DEBUG:  Plan is router executable
 50	10	anjanette	19519
--- error out for queries with aggregates
 SELECT avg(word_count)
 	FROM articles
 	WHERE author_id = 2;
@@ -500,6 +499,16 @@ DETAIL:  distribution column value: 2
  12356.400000000000
 (1 row)
 
+-- error out on unsupported aggregate
+SET client_min_messages to 'NOTICE';
+CREATE AGGREGATE public.invalid(int) (
+    sfunc = int4pl,
+    stype = int
+);
+SELECT invalid(word_count) FROM articles;
+ERROR:  unsupported aggregate function invalid
+DROP AGGREGATE invalid(int);
+SET client_min_messages to 'DEBUG2';
 -- max, min, sum, count is somehow implemented
 -- differently in distributed planning 
 SELECT max(word_count) as max, min(word_count) as min,
diff --git a/src/test/regress/sql/multi_simple_queries.sql b/src/test/regress/sql/multi_simple_queries.sql
index 8a03f06c9..7b4606b51 100644
--- a/src/test/regress/sql/multi_simple_queries.sql
+++ b/src/test/regress/sql/multi_simple_queries.sql
@@ -271,11 +271,24 @@ SELECT id
 -- copying from a single shard table does not require the master query
 COPY articles_single_shard TO stdout;
 
--- error out for queries with aggregates
 SELECT avg(word_count)
 	FROM articles
 	WHERE author_id = 2;
 
+-- error out on unsupported aggregate
+SET client_min_messages to 'NOTICE';
+
+CREATE AGGREGATE public.invalid(int) (
+    sfunc = int4pl,
+    stype = int
+);
+
+SELECT invalid(word_count) FROM articles;
+
+DROP AGGREGATE invalid(int);
+
+SET client_min_messages to 'DEBUG2';
+
 -- max, min, sum, count is somehow implemented
 -- differently in distributed planning 
 SELECT max(word_count) as max, min(word_count) as min,
@@ -313,5 +326,4 @@ SELECT * FROM articles TABLESAMPLE BERNOULLI (0) WHERE author_id = 1;
 SELECT * FROM articles TABLESAMPLE SYSTEM (100) WHERE author_id = 1 ORDER BY id;
 SELECT * FROM articles TABLESAMPLE BERNOULLI (100) WHERE author_id = 1 ORDER BY id;
 
-
 SET client_min_messages to 'NOTICE';