diff --git a/src/test/regress/expected/polymorphism.out b/src/test/regress/expected/polymorphism.out
index bae04a2719b..4d1fc2beb04 100644
--- a/src/test/regress/expected/polymorphism.out
+++ b/src/test/regress/expected/polymorphism.out
@@ -623,7 +623,8 @@ where histogram_bounds is not null;
 (1 row)
 
 -- such functions must protect themselves if varying element type isn't OK
-select max(histogram_bounds) from pg_stats;
+-- (WHERE clause here is to avoid possibly getting a collation error instead)
+select max(histogram_bounds) from pg_stats where tablename = 'pg_am';
 ERROR:  cannot compare arrays of different element types
 -- test variadic polymorphic functions
 create function myleast(variadic anyarray) returns anyelement as $$
diff --git a/src/test/regress/sql/polymorphism.sql b/src/test/regress/sql/polymorphism.sql
index 2baebe93235..50e6905d4ca 100644
--- a/src/test/regress/sql/polymorphism.sql
+++ b/src/test/regress/sql/polymorphism.sql
@@ -433,7 +433,8 @@ select distinct array_ndims(histogram_bounds) from pg_stats
 where histogram_bounds is not null;
 
 -- such functions must protect themselves if varying element type isn't OK
-select max(histogram_bounds) from pg_stats;
+-- (WHERE clause here is to avoid possibly getting a collation error instead)
+select max(histogram_bounds) from pg_stats where tablename = 'pg_am';
 
 -- test variadic polymorphic functions