diff --git a/src/UsersBatch.cs b/src/UsersBatch.cs
index fc851b6..d5bcd31 100644
--- a/src/UsersBatch.cs
+++ b/src/UsersBatch.cs
@@ -22,7 +22,7 @@ public async Task<IEnumerable<User>> UpsertUsersAsync(IEnumerable<User> users, b
             var body = new Dictionary<string, object>
             {
                 { "users", users },
-                { "override", overrideExisting },
+                { "override_existing", overrideExisting },
             };
             var request = _client.BuildAppRequest("users/", HttpMethod.Post);
             request.SetJsonBody(StreamJsonConverter.SerializeObject(body));