diff --git a/web/roles/role-actions-menu.react.js b/web/roles/role-actions-menu.react.js
--- a/web/roles/role-actions-menu.react.js
+++ b/web/roles/role-actions-menu.react.js
@@ -5,7 +5,10 @@
 
 import { useModalContext } from 'lib/components/modal-provider.react.js';
 import SWMansionIcon from 'lib/components/swmansion-icon.react.js';
-import { useRoleUserSurfacedPermissions } from 'lib/shared/thread-utils.js';
+import {
+  roleIsDefaultRole,
+  useRoleUserSurfacedPermissions,
+} from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { useRoleDeletableAndEditableStatus } from 'lib/utils/role-utils.js';
 
@@ -26,8 +29,8 @@
   const { threadInfo, roleName } = props;
   const { pushModal } = useModalContext();
 
-  const defaultRoleID = Object.keys(threadInfo.roles).find(
-    roleID => threadInfo.roles[roleID].isDefault,
+  const defaultRoleID = Object.keys(threadInfo.roles).find(roleID =>
+    roleIsDefaultRole(threadInfo.roles[roleID]),
   );
   invariant(defaultRoleID, 'default role should exist');