diff --git a/config/environments/test.rb b/config/environments/test.rb
index cfba7d0307..2e14aea9c3 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -52,7 +52,17 @@ Openfoodnetwork::Application.configure do
   # config.active_record.schema_format = :sql
 
   # Print deprecation notices to the stderr
-  config.active_support.deprecation = :stderr
+  # config.active_support.deprecation = :stderr
+
+  # Fail tests on deprecated code unless it's a known case to solve.
+  ActiveSupport::Deprecation.behavior = ->(message, callstack, deprecation_horizon, gem_name) do
+    allowed_warnings = [
+      # List strings here to allow matching deprecations.
+    ]
+    unless allowed_warnings.any? { |pattern| message.match(pattern) }
+      ActiveSupport::Deprecation::DEFAULT_BEHAVIORS[:raise].call(message, callstack, deprecation_horizon, gem_name)
+    end
+  end
 
   config.active_job.queue_adapter = :test
 end
diff --git a/config/initializers/deprecations.rb b/config/initializers/deprecations.rb
new file mode 100644
index 0000000000..76d05f9acd
--- /dev/null
+++ b/config/initializers/deprecations.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+ActiveSupport::Notifications.subscribe(/deprecation/) do |_name, _start, _finish, _id, payload|
+  e = ActiveSupport::DeprecationException.new(payload[:message])
+  e.set_backtrace(payload[:callstack].map(&:to_s))
+
+  Bugsnag.notify(e) do |report|
+    report.severity = "warning"
+    report.add_tab(
+      :deprecation,
+      payload.except(:callstack),
+    )
+  end
+end
diff --git a/lib/reporting/reports/bulk_coop/customer_payments.rb b/lib/reporting/reports/bulk_coop/customer_payments.rb
index 97752b3feb..4e4da4ce12 100644
--- a/lib/reporting/reports/bulk_coop/customer_payments.rb
+++ b/lib/reporting/reports/bulk_coop/customer_payments.rb
@@ -21,15 +21,15 @@ module Reporting
         private
 
         def customer_payments_total_cost(line_items)
-          unique_orders(line_items).sum(&:total)
+          unique_orders(line_items).map(&:total).sum(&:to_f)
         end
 
         def customer_payments_amount_owed(line_items)
-          unique_orders(line_items).sum(&:new_outstanding_balance)
+          unique_orders(line_items).map(&:new_outstanding_balance).sum(&:to_f)
         end
 
         def customer_payments_amount_paid(line_items)
-          unique_orders(line_items).sum(&:payment_total)
+          unique_orders(line_items).map(&:payment_total).sum(&:to_f)
         end
 
         def unique_orders(line_items)