diff --git a/lib/apipie/generator/swagger/param_description/builder.rb b/lib/apipie/generator/swagger/param_description/builder.rb
index eb695b1f..5fca774a 100644
--- a/lib/apipie/generator/swagger/param_description/builder.rb
+++ b/lib/apipie/generator/swagger/param_description/builder.rb
@@ -1,7 +1,7 @@
 class Apipie::Generator::Swagger::ParamDescription::Builder
   # @param [Apipie::ParamDescription] param_description
   # @param [TrueClass, FalseClass] in_schema
-  # @param [Apipie::MethodDescription] controller_method
+  # @param [Apipie::MethodDescription, nil] controller_method
   def initialize(param_description, in_schema:, controller_method:)
     @param_description = param_description
     @in_schema = in_schema
@@ -98,8 +98,8 @@ def required_from_path?
   def warn_optional_without_default_value(definition)
     if !required? && !definition.key?(:default)
       method_id =
-        if @param_description.is_a?(Apipie::ResponseDescriptionAdapter::PropDesc)
-          @controller_method
+        if @controller_method.present? && @param_description.is_a?(Apipie::ResponseDescriptionAdapter::PropDesc)
+          @controller_method.method_name
         else
           Apipie::Generator::Swagger::MethodDescription::Decorator.new(@controller_method).ruby_name
         end
diff --git a/lib/apipie/generator/swagger/param_description/type.rb b/lib/apipie/generator/swagger/param_description/type.rb
index f35c49b7..37c799fa 100644
--- a/lib/apipie/generator/swagger/param_description/type.rb
+++ b/lib/apipie/generator/swagger/param_description/type.rb
@@ -114,7 +114,11 @@ def validator
   def warn_hash_without_internal_typespec
     method_id =
       if @param_description.is_a?(Apipie::ResponseDescriptionAdapter::PropDesc)
-        @controller_method.method
+        if @controller_method.present?
+          @controller_method.method_name
+        else
+          Apipie::Generator::Swagger::MethodDescription::Decorator.new(nil).ruby_name
+        end
       else
         Apipie::Generator::Swagger::MethodDescription::Decorator.new(@param_description.method_description).ruby_name
       end
diff --git a/spec/lib/apipie/generator/swagger/param_description/builder_spec.rb b/spec/lib/apipie/generator/swagger/param_description/builder_spec.rb
index db7479df..c2fb5de0 100644
--- a/spec/lib/apipie/generator/swagger/param_description/builder_spec.rb
+++ b/spec/lib/apipie/generator/swagger/param_description/builder_spec.rb
@@ -145,6 +145,36 @@
             /is optional but default value is not specified/
           ).to_stderr
         end
+
+        context 'and param is a prop desc' do
+          let(:param_description) do
+            Apipie.prop(:param, 'object', param_description_options, [])
+          end
+
+          context 'with a delegated controller method' do
+            let(:method_desc) do
+              Apipie::Generator::Swagger::MethodDescription::Decorator.new(
+                Apipie::MethodDescription.new(:show, resource_desc, dsl_data)
+              )
+            end
+
+            it 'warns' do
+              expect { subject }.to output(
+                /is optional but default value is not specified/
+              ).to_stderr
+            end
+          end
+
+          context 'with a nil controller method' do
+            let(:method_desc) { nil }
+
+            it 'warns' do
+              expect { subject }.to output(
+                /is optional but default value is not specified/
+              ).to_stderr
+            end
+          end
+        end
       end
     end
   end
diff --git a/spec/lib/apipie/generator/swagger/param_description/type_spec.rb b/spec/lib/apipie/generator/swagger/param_description/type_spec.rb
index dbbe34f0..f08396ec 100644
--- a/spec/lib/apipie/generator/swagger/param_description/type_spec.rb
+++ b/spec/lib/apipie/generator/swagger/param_description/type_spec.rb
@@ -3,7 +3,6 @@
 describe Apipie::Generator::Swagger::ParamDescription::Type do
   let(:validator_options) { {} }
   let(:param_description_options) { {}.merge(validator_options) }
-  let(:with_null) { false }
   let(:http_method) { :GET }
   let(:path) { '/api' }
   let(:validator) { String }
@@ -63,9 +62,11 @@
     )
   end
 
+  let(:controller_method) { 'index' }
+
   let(:type_definition) do
     described_class.
-      new(param_description, with_null: with_null, controller_method: 'index').
+      new(param_description, with_null: false, controller_method: controller_method).
       to_hash
   end
 
@@ -178,6 +179,32 @@
       it 'outputs a hash without internal typespec warning' do
         expect { subject }.to output(/is a generic Hash without an internal type specification/).to_stderr
       end
+
+      context 'and param is a prop desc' do
+        let(:param_description) do
+          Apipie.prop(param_description_name, 'object', {}, [])
+        end
+
+        context 'with a delegated controller method' do
+          let(:controller_method) do
+            Apipie::Generator::Swagger::MethodDescription::Decorator.new(
+              method_desc
+            )
+          end
+
+          it 'outputs a hash without internal typespec warning' do
+            expect { subject }.to output(/is a generic Hash without an internal type specification/).to_stderr
+          end
+        end
+
+        context 'and controller method is nil' do
+          let(:controller_method) { nil }
+
+          it 'outputs a hash without internal typespec warning' do
+            expect { subject }.to output(/is a generic Hash without an internal type specification/).to_stderr
+          end
+        end
+      end
     end
   end
 end