diff --git a/pkgs/by-name/po/postgresqlTestHook/postgresql-test-hook.sh b/pkgs/by-name/po/postgresqlTestHook/postgresql-test-hook.sh
index 41762121882b..f36a384b6fb4 100644
--- a/pkgs/by-name/po/postgresqlTestHook/postgresql-test-hook.sh
+++ b/pkgs/by-name/po/postgresqlTestHook/postgresql-test-hook.sh
@@ -54,7 +54,7 @@ EOF
     false
   fi
   echo 'initializing postgresql'
-  initdb -U postgres
+  initdb --encoding=UTF8 -U postgres
 
   echo "$postgresqlExtraSettings" >>"$PGDATA/postgresql.conf"