diff --git a/lib/types/link-types.js b/lib/types/link-types.js
--- a/lib/types/link-types.js
+++ b/lib/types/link-types.js
@@ -21,8 +21,8 @@
   +primary: boolean,
   +role: string,
   +communityID: string,
-  +expirationTime: number,
-  +limitOfUses: number,
+  +expirationTime: ?number,
+  +limitOfUses: ?number,
   +numberOfUses: number,
 };