diff --git a/CHANGELOG.md b/CHANGELOG.md
index 43516654e..ea24dcb28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Register the Active Record and Action View integrations when the gem is required, instead of from the railtie initializer
 - Add a top-level `null` option to the `add_monetize`/`monetize` migration helpers (#775)
+- Fix `MoneyRails::ActiveJob::MoneySerializer` not being registered on Rails 8.1+, and on older versions without eager loading (#779)
 
 ## 3.0.0
 
diff --git a/lib/money-rails/hooks.rb b/lib/money-rails/hooks.rb
index 178fa2ed6..bc8e009b9 100644
--- a/lib/money-rails/hooks.rb
+++ b/lib/money-rails/hooks.rb
@@ -37,15 +37,10 @@ def self.init
         require "money-rails/mongoid/money"
       end
 
-      # For ActiveSupport
-      ActiveSupport.on_load(:active_job) do
-        if defined?(::ActiveJob::Serializers)
-          require "money-rails/active_job/money_serializer"
-          Rails.application.config.active_job.tap do |config|
-            config.custom_serializers ||= []
-            config.custom_serializers << MoneyRails::ActiveJob::MoneySerializer
-          end
-        end
+      # For Active Job
+      if defined?(::ActiveJob::Serializers)
+        require "money-rails/active_job/money_serializer"
+        ::ActiveJob::Serializers.add_serializers(MoneyRails::ActiveJob::MoneySerializer)
       end
     end
   end
diff --git a/spec/active_job/money_serializer_spec.rb b/spec/active_job/money_serializer_spec.rb
index 439d597d7..743e304e8 100644
--- a/spec/active_job/money_serializer_spec.rb
+++ b/spec/active_job/money_serializer_spec.rb
@@ -25,5 +25,13 @@
     describe "#deserialize" do
       it { expect(described_class.deserialize(serialized_money)).to eq(money) }
     end
+
+    describe "Active Job registration" do
+      it "round-trips Money through Active Job argument serialization" do
+        serialized = ActiveJob::Arguments.serialize([money])
+
+        expect(ActiveJob::Arguments.deserialize(serialized)).to eq([money])
+      end
+    end
   end
 end
diff --git a/spec/dummy/config/application.rb b/spec/dummy/config/application.rb
index 2a5357c0e..a5bb7045d 100644
--- a/spec/dummy/config/application.rb
+++ b/spec/dummy/config/application.rb
@@ -4,6 +4,14 @@
 require "logger"
 
 require "active_record/railtie" unless ENV["BUNDLE_GEMFILE"]&.include?("mongoid")
+# The Mongoid gemfiles depend on Action Pack only, not the full rails gem, so the
+# activejob gem may be unavailable. Load it only when present (the serializer specs
+# are guarded by `defined?(ActiveJob::Serializers)`).
+begin
+  require "active_job/railtie"
+rescue LoadError
+  nil
+end
 require "action_controller/railtie"
 
 Bundler.require