diff --git a/lib/permissions/special-roles.js b/lib/permissions/special-roles.js
--- a/lib/permissions/special-roles.js
+++ b/lib/permissions/special-roles.js
@@ -28,19 +28,23 @@
 });
 
 function patchRoleInfoWithSpecialRole(role: RoleInfo): RoleInfo {
+  // We removed the `.isDefault` field from `RoleInfo`, but persisted
+  // `RoleInfo`s will still have the field until this migration.
+  // $FlowIgnore[prop-missing]
+  const { isDefault, ...roleSansIsDefault } = role;
   if (roleIsDefaultRole(role)) {
     return {
-      ...role,
+      ...roleSansIsDefault,
       specialRole: specialRoles.DEFAULT_ROLE,
     };
   } else if (roleIsAdminRole(role)) {
     return {
-      ...role,
+      ...roleSansIsDefault,
       specialRole: specialRoles.ADMIN_ROLE,
     };
   } else {
     return {
-      ...role,
+      ...roleSansIsDefault,
       specialRole: null,
     };
   }