diff --git a/lib/python/propex.py b/lib/python/propex.py
index 7de0668..3993d2c 100644
--- a/lib/python/propex.py
+++ b/lib/python/propex.py
@@ -30,13 +30,13 @@ class CustomProperty(property, Generic[T]):
     def __get__(self, obj: Optional[O], cls: Type[O]):
         if obj is None:
             return self
-        raise AttributeError(f"Cannot read property {self.property_name} of {obj:r}")
+        raise AttributeError(f"Cannot read property {self.property_name} of {obj!r}")
 
     def __set__(self, obj: O, value: T):
-        raise AttributeError(f"Cannot write property {self.property_name} of {obj:r}")
+        raise AttributeError(f"Cannot write property {self.property_name} of {obj!r}")
 
     def __delete__(self, obj: O):
-        raise AttributeError(f"Cannot delete property {self.property_name} of {obj:r}")
+        raise AttributeError(f"Cannot delete property {self.property_name} of {obj!r}")
 
 
 class CachedProperty(CustomProperty[T]):
diff --git a/lib/python/steamutil.py b/lib/python/steamutil.py
index 7926bea..5c98277 100644
--- a/lib/python/steamutil.py
+++ b/lib/python/steamutil.py
@@ -8,7 +8,7 @@ from pathlib import Path
 from typing import List, Iterable, Dict, Literal, Mapping, Tuple, Callable, Optional, Union, Any, cast, overload
 
 from vdfparser import VdfParser, DeepDict, AppInfoFile, LowerCaseNormalizingDict, dd_getpath
-from propex import CachedProperty, DictPathProperty, DictPathRoProperty
+from propex import CachedProperty, SettableCachedProperty, DictPathProperty, DictPathRoProperty
 
 
 _vdf = VdfParser()
@@ -405,7 +405,7 @@ class Steam:
     def appinfo(self) -> AppInfoFile:
         return AppInfoFile.open(self.appinfo_vdf)
 
-    @CachedProperty
+    @SettableCachedProperty
     def steamplay_manifest(self) -> DeepDict:
         with self.appinfo as info:
             return info[891390]["appinfo"]