diff --git a/lib/twitter-ads/campaign/line_item.rb b/lib/twitter-ads/campaign/line_item.rb
index 5142e40e..dac6a598 100644
--- a/lib/twitter-ads/campaign/line_item.rb
+++ b/lib/twitter-ads/campaign/line_item.rb
@@ -85,5 +85,16 @@ def targeting_criteria(id = nil, opts = {})
       id ? TargetingCriteria.load(account, id, opts) : TargetingCriteria.all(account, @id, opts)
     end
 
+    def to_params
+      params = super
+
+      # If automatically_set_bid is set, bid_type must not be set.
+      params.delete(:bid_type) if params[:automatically_select_bid]
+
+      # advertiser_user_id is currently beta-only and causes an error when sent.
+      params.delete(:advertiser_user_id)
+
+      params
+    end
   end
 end