diff --git a/Python/hbayesdm/base.py b/Python/hbayesdm/base.py
index 73b342b7..26940a6f 100644
--- a/Python/hbayesdm/base.py
+++ b/Python/hbayesdm/base.py
@@ -645,10 +645,10 @@ def _designate_stan_model(self, model: str) -> StanModel:
         if getattr(os, 'getuid', None) is None:
             uid = 'windows'
         else:
-            uid = os.getuid()
+            uid = str(os.getuid())
 
         cache_file = tempdir / (
-            'cached-hBayesDM_model-%s-pystan_%s_user-%d.pkl' %
+            'cached-hBayesDM_model-%s-pystan_%s_user-%s.pkl' %
             (model, _pystan_version, uid)
         )