diff --git a/app/models/cart_item/reservation.rb b/app/models/cart_item/reservation.rb
index 3474eb87a..2d54022b0 100644
--- a/app/models/cart_item/reservation.rb
+++ b/app/models/cart_item/reservation.rb
@@ -86,7 +86,7 @@ class CartItem::Reservation < CartItem::BaseItem
                    slot_rate
                  end
     # subtract free minutes from prepaid packs
-    if real_price.positive? && options[:prepaid][:minutes] >= 0
+    if real_price.positive? && options[:prepaid][:minutes]&.positive?
       consumed = slot_minutes
       consumed = options[:prepaid][:minutes] if slot_minutes > options[:prepaid][:minutes]
       real_price = (slot_minutes - consumed) * (slot_rate / MINUTES_PER_HOUR)
diff --git a/test/integration/prices/compute_test.rb b/test/integration/prices/compute_test.rb
index 47e95a162..4b30cf9e2 100644
--- a/test/integration/prices/compute_test.rb
+++ b/test/integration/prices/compute_test.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'test_helper'
+
 module Prices
   class AsAdminTest < ActionDispatch::IntegrationTest
     setup do