diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -1083,6 +1083,12 @@
   return !!memberInfo.permissions[threadPermissions.CHANGE_ROLE]?.value;
 }
 
+function roleIsDefaultRole(
+  roleInfo: ?ClientLegacyRoleInfo | ?RoleInfo,
+): boolean {
+  return !!(roleInfo && roleInfo.isDefault);
+}
+
 function roleIsAdminRole(roleInfo: ?ClientLegacyRoleInfo | ?RoleInfo): boolean {
   return !!(roleInfo && !roleInfo.isDefault && roleInfo.name === 'Admins');
 }
@@ -1845,6 +1851,7 @@
   threadInfoFromRawThreadInfo,
   threadTypeDescriptions,
   memberHasAdminPowers,
+  roleIsDefaultRole,
   roleIsAdminRole,
   threadHasAdminRole,
   identifyInvalidatedThreads,