diff --git a/esmvalcore/_recipe/from_datasets.py b/esmvalcore/_recipe/from_datasets.py
index e133af1447..5bfab6f96a 100644
--- a/esmvalcore/_recipe/from_datasets.py
+++ b/esmvalcore/_recipe/from_datasets.py
@@ -6,7 +6,7 @@
 import re
 from copy import deepcopy
 from functools import partial
-from typing import TYPE_CHECKING, Any, Iterable, Mapping, Sequence
+from typing import TYPE_CHECKING, Any, Dict, Iterable, Mapping, Sequence
 
 from nested_lookup import nested_delete
 
@@ -17,8 +17,8 @@
 
 logger = logging.getLogger(__name__)
 
-Recipe = dict[str, Any]
-Facets = dict[str, Any]
+Recipe = Dict[str, Any]
+Facets = Dict[str, Any]
 
 
 def _datasets_to_raw_recipe(datasets: Iterable[Dataset]) -> Recipe:
diff --git a/esmvalcore/dataset.py b/esmvalcore/dataset.py
index 819febc2aa..3926289067 100644
--- a/esmvalcore/dataset.py
+++ b/esmvalcore/dataset.py
@@ -9,7 +9,7 @@
 from copy import deepcopy
 from fnmatch import fnmatchcase
 from pathlib import Path
-from typing import Any, Iterator, Sequence
+from typing import Any, Iterator, Sequence, Union
 
 from iris.cube import Cube
 
@@ -39,7 +39,7 @@
 
 logger = logging.getLogger(__name__)
 
-File = esgf.ESGFFile | local.LocalFile
+File = Union[esgf.ESGFFile, local.LocalFile]
 
 
 def _augment(base: dict, update: dict):
diff --git a/setup.cfg b/setup.cfg
index f966524dba..3bf09d26f9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -36,6 +36,7 @@ include_trailing_comma = true
 
 [mypy]
 # see mypy.readthedocs.io/en/stable/command_line.html
+python_version = 3.9
 ignore_missing_imports = True
 files = esmvalcore, tests