diff --git a/lib/associations/associations.rb b/lib/associations/associations.rb
index 60d9f3a..3ffd77d 100644
--- a/lib/associations/associations.rb
+++ b/lib/associations/associations.rb
@@ -8,14 +8,16 @@ def self.extended(base)
 
       def has_many(association_id, scope = nil, **options, &extension)
         if options[:through]
-          klass_name = association_id.to_s.classify
-          klass = klass_name.safe_constantize
+          source_association_name = options[:source]&.to_s || association_id.to_s.singularize
+
+          through_klass = reflect_on_association(options[:through])&.klass
+          klass = through_klass&.reflect_on_association(source_association_name)&.klass
 
           if klass && klass < ActiveHash::Base
             define_method(association_id) do
               join_models = send(options[:through])
               join_models.flat_map do |join_model|
-                join_model.send(association_id.to_s.singularize)
+                join_model.send(source_association_name)
               end.uniq
             end
 
diff --git a/spec/associations/active_record_extensions_spec.rb b/spec/associations/active_record_extensions_spec.rb
index be773cf..50b6fb9 100644
--- a/spec/associations/active_record_extensions_spec.rb
+++ b/spec/associations/active_record_extensions_spec.rb
@@ -234,6 +234,56 @@ def define_doctor_classes
 
           expect(patient.physicians).to contain_exactly(physician1, physician2)
         end
+
+        describe "with the :source option" do
+          before do
+            # NOTE: Removing the Patient#physicians association and adding Patient#doctors
+            Patient._reflections.delete('physicians')
+            Patient.class_eval do
+              define_method(:physicians) { raise NoMethodError, "The #physicians association is removed in this spec, use #doctors" }
+              define_method(:physicians=) { |_| raise NoMethodError, "The #physicians association is removed in this spec, use #doctors" }
+            end
+            Patient.has_many :doctors, through: :appointments, source: :physician
+          end
+
+          it "finds ActiveHash records through the join model" do
+            patient = Patient.create!
+
+            physician = Physician.last
+            Appointment.create!(physician: physician, patient: patient)
+
+            expect(patient.doctors).to contain_exactly(physician)
+          end
+        end
+
+        describe ":through when the join model uses an aliased association" do
+          before do
+            # NOTE: Removing the Appointment#physician association and adding Appointment#doctor
+            Appointment._reflections.delete('physician')
+            Appointment.class_eval do
+              define_method(:physician) { raise NoMethodError, "The #physician association is removed in this spec, use #doctor" }
+              define_method(:physician=) { |_| raise NoMethodError, "The #physician association is removed in this spec, use #doctor" }
+            end
+            Appointment.belongs_to :doctor, class_name: 'Physician', foreign_key: :physician_id
+
+            # NOTE: Removing the Patient#physicians association and adding Patient#doctors
+            Patient._reflections.delete('physicians')
+            Patient.class_eval do
+              define_method(:physicians) { raise NoMethodError, "The #physicians association is removed in this spec, use #doctors" }
+              define_method(:physicians=) { |_| raise NoMethodError, "The #physicians association is removed in this spec, use #doctors" }
+            end
+            Patient.has_many :doctors, through: :appointments
+          end
+
+          it "finds ActiveHash records through the join model" do
+            patient = Patient.create!
+
+            physician = Physician.last
+            Appointment.create!(doctor: physician, patient: patient)
+
+            expect(patient.doctors).to contain_exactly(physician)
+          end
+        end
       end
 
       describe "with a lambda" do