diff --git a/lib/transaction.rb b/lib/transaction.rb
index 2c56271f252211d8f85bdac501f8d7f36a93d05a..e173aac2281daddb8b83a7d8f00fea219e82f972 100644
--- a/lib/transaction.rb
+++ b/lib/transaction.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "bigdecimal"
+require "bigdecimal/util"
 
 require_relative "trust_level_repo"
 
@@ -24,7 +25,7 @@ class Transaction
 			TrustLevelRepo.new.find(customer), customer.declines,
 			payment_method || customer.payment_methods.then(&:default_payment_method)
 		]).then do |(lock, tl, declines, selected_method)|
-			raise "Declined" unless tl.credit_card_transaction?(amount, declines)
+			raise "Declined" unless tl.credit_card_transaction?(amount.to_d, declines)
 			raise "Too many payments recently" if lock == 1
 			raise "No valid payment method on file" unless selected_method