diff --git a/lib/kangaru/validation/attribute_validator.rb b/lib/kangaru/validation/attribute_validator.rb
index 3a1b727..cb3d940 100644
--- a/lib/kangaru/validation/attribute_validator.rb
+++ b/lib/kangaru/validation/attribute_validator.rb
@@ -16,16 +16,8 @@ def validate(validator, **params)
 
       private
 
-      def validator_name(validator)
-        validator.to_s.to_class_name(suffix: :validator)
-      end
-
       def load_validator(validator:, **params)
-        name = validator_name(validator)
-
-        raise "#{name} is not defined" unless Validators.const_defined?(name)
-
-        Validators.const_get(name).new(model:, attribute:, **params)
+        Validators.get(validator).new(model:, attribute:, **params)
       end
     end
   end
diff --git a/spec/features/custom_validators_spec.rb b/spec/features/custom_validators_spec.rb
new file mode 100644
index 0000000..aa4ec35
--- /dev/null
+++ b/spec/features/custom_validators_spec.rb
@@ -0,0 +1,111 @@
+RSpec.describe "a validatable model using custom validator rules" do
+  subject(:model) { SomeGem::Model.new(**attributes) }
+
+  include_context :kangaru_initialised
+
+  let(:attributes) { { attribute: value } }
+
+  let(:value) { :valid }
+
+  let(:model_class) do
+    <<~RUBY
+      module SomeGem
+        class Model
+          include Kangaru::Validatable
+
+          #{validations}
+
+          attr_reader :attribute
+
+          def initialize(attribute:)
+            @attribute = attribute
+          end
+        end
+      end
+    RUBY
+  end
+
+  let(:validator_class) do
+    <<~RUBY
+      module SomeGem
+        module Validators
+          class CustomValidator < Kangaru::Validator
+            def validate
+              return if value == :valid
+
+              add_error!("is invalid")
+            end
+          end
+        end
+      end
+    RUBY
+  end
+
+  before do
+    gem.path("validators", ext: nil).mkdir
+    gem.path("validators", "custom_validator").write(validator_class)
+
+    gem.path("model").write(model_class)
+
+    gem.load!
+  end
+
+  describe "#validate" do
+    subject(:validate) { model.validate }
+
+    let(:validations) do
+      <<~RUBY
+        validates :attribute, #{validator_name}: true
+      RUBY
+    end
+
+    context "when validator with given name is not defined" do
+      let(:validator_name) { :undefined }
+
+      it "raises an error" do
+        expect { validate }.to raise_error("UndefinedValidator is not defined")
+      end
+    end
+
+    context "when validator with given name is defined" do
+      let(:validator_name) { :custom }
+
+      context "and model is not valid" do
+        let(:value) { :invalid }
+
+        it "does not raise any errors" do
+          expect { validate }.not_to raise_error
+        end
+
+        it "is not valid" do
+          expect(model).not_to be_valid
+        end
+
+        it "adds an error" do
+          expect { validate }.to change { model.errors.count }.by(1)
+        end
+
+        it "sets the expected message" do
+          validate
+          expect(model.errors.last.full_message).to eq("Attribute is invalid")
+        end
+      end
+
+      context "and model is valid" do
+        let(:value) { :valid }
+
+        it "does not raise any errors" do
+          expect { validate }.not_to raise_error
+        end
+
+        it "is valid" do
+          expect(model).to be_valid
+        end
+
+        it "does not add any errors" do
+          expect { validate }.not_to change { model.errors }
+        end
+      end
+    end
+  end
+end