diff --git a/src/test/regress/expected/pg15.out b/src/test/regress/expected/pg15.out
index 76a89706e..739985d4f 100644
--- a/src/test/regress/expected/pg15.out
+++ b/src/test/regress/expected/pg15.out
@@ -1555,8 +1555,8 @@ CREATE DATABASE mydatabase
             ENCODING = 'UTF8'
             STRATEGY = 'wal_log'
             LOCALE = ''
-            LC_COLLATE = 'en_US.utf8'
-            LC_CTYPE = 'en_US.utf8'
+            LC_COLLATE = 'POSIX'
+            LC_CTYPE = 'POSIX'
             ICU_LOCALE = ''
             LOCALE_PROVIDER = 'icu'
             COLLATION_VERSION = '1.0'
diff --git a/src/test/regress/sql/pg15.sql b/src/test/regress/sql/pg15.sql
index 32ced0750..ddc02b2e4 100644
--- a/src/test/regress/sql/pg15.sql
+++ b/src/test/regress/sql/pg15.sql
@@ -1002,8 +1002,8 @@ CREATE DATABASE mydatabase
             ENCODING = 'UTF8'
             STRATEGY = 'wal_log'
             LOCALE = ''
-            LC_COLLATE = 'en_US.utf8'
-            LC_CTYPE = 'en_US.utf8'
+            LC_COLLATE = 'POSIX'
+            LC_CTYPE = 'POSIX'
             ICU_LOCALE = ''
             LOCALE_PROVIDER = 'icu'
             COLLATION_VERSION = '1.0'