diff --git a/website/server/controllers/api-v3/user.js b/website/server/controllers/api-v3/user.js
index c04c3ded38..eed3992dc2 100644
--- a/website/server/controllers/api-v3/user.js
+++ b/website/server/controllers/api-v3/user.js
@@ -445,7 +445,7 @@ api.castSpell = {
       // Only return some fields.
       // See comment above on why we can't just select the necessary fields when querying
       partyMembersRes = partyMembersRes.map(partyMember => {
-        return common.pickDeep(partyMember, common.splitWhitespace(partyMembersFields));
+        return common.pickDeep(partyMember.toJSON(), common.splitWhitespace(partyMembersFields));
       });
 
       res.respond(200, {