diff --git a/app/src/types/api.ts b/app/src/types/api.ts
index 047628d..1783cbb 100644
--- a/app/src/types/api.ts
+++ b/app/src/types/api.ts
@@ -42,10 +42,10 @@ export function isLoginResponse(obj: unknown): obj is LoginResponse {
     obj !== null &&
     'user' in obj &&
     isUser(obj.user) &&
-    'sessionId' in obj &&
-    typeof (obj as LoginResponse).sessionId === 'string' &&
-    'expiresAt' in obj &&
-    typeof (obj as LoginResponse).expiresAt === 'string'
+    (!('sessionId' in obj) ||
+      typeof (obj as LoginResponse).sessionId === 'string') &&
+    (!('expiresAt' in obj) ||
+      typeof (obj as LoginResponse).expiresAt === 'string')
   );
 }
 
diff --git a/app/src/types/models.ts b/app/src/types/models.ts
index 8041cb8..d95e27a 100644
--- a/app/src/types/models.ts
+++ b/app/src/types/models.ts
@@ -46,7 +46,10 @@ export enum UserRole {
  * Type guard to check if a value is a valid UserRole
  */
 export function isUserRole(value: unknown): value is UserRole {
-  return typeof value === 'string' && value in UserRole;
+  return (
+    typeof value === 'string' &&
+    Object.values(UserRole).includes(value as UserRole)
+  );
 }
 
 export enum Theme {