diff --git a/setup.cfg b/setup.cfg
index 2bff8c77..dcf85b3f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -52,6 +52,6 @@ known_third_party =
   xlrd
 
 [mypy]
-python_version = 3.9
+python_version = 3.10
 strict = True
 warn_unreachable = True
diff --git a/stdnum/eu/vat.py b/stdnum/eu/vat.py
index 6c2e5a26..3083fb6d 100644
--- a/stdnum/eu/vat.py
+++ b/stdnum/eu/vat.py
@@ -56,7 +56,7 @@
 country code of gr while for VAT purposes el is used instead. For Northern
 Ireland numbers are prefixed with xi of United Kingdom numbers."""
 
-_country_modules = dict()
+_country_modules: dict[str, NumberValidationModule | None] = {}
 
 vies_wsdl = 'https://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl'
 """The WSDL URL of the VAT Information Exchange System (VIES)."""
diff --git a/stdnum/util.py b/stdnum/util.py
index bd5d1056..aaaee91c 100644
--- a/stdnum/util.py
+++ b/stdnum/util.py
@@ -256,7 +256,7 @@ def get_cc_module(cc: str, name: str) -> NumberValidationModule | None:
 
 
 # this is a cache of SOAP clients
-_soap_clients = {}
+_soap_clients: dict[tuple[str, float, bool | str], Any] = {}
 
 
 def _get_zeep_soap_client(