diff --git a/class.go b/class.go
index c2d3b5e..f4b282b 100644
--- a/class.go
+++ b/class.go
@@ -3,8 +3,10 @@ package mruby
 type methodTable map[Symbol]*Method
 type mt = methodTable
 
+var _ RBasic = &RClass{}
+
 type RClass struct {
-	RBasic
+	object
 	super *RClass
 	mt
 	iv
@@ -84,4 +86,9 @@ func initClass(mrb *State) {
 	basicObject.class = classClass
 	objectClass.class = classClass
 	moduleClass.class = classClass
+
+	mrb.DefineConstById(basicObject, mrb.Intern("BasicObject"), NewObjectValue(basicObject))
+	mrb.DefineConstById(objectClass, mrb.Intern("Object"), NewObjectValue(objectClass))
+	mrb.DefineConstById(objectClass, mrb.Intern("Module"), NewObjectValue(moduleClass))
+	mrb.DefineConstById(objectClass, mrb.Intern("Class"), NewObjectValue(classClass))
 }
diff --git a/feature_test.go b/feature_test.go
index 466d5c5..34219ab 100644
--- a/feature_test.go
+++ b/feature_test.go
@@ -95,6 +95,15 @@ func (feat *RubyFeature) thereShouldReturnSymbol(expected string) error {
 	return nil
 }
 
+func (feat *RubyFeature) thereShouldReturnObject() error {
+	_, ok := feat.ret.(mruby.RBasic)
+	if !ok {
+		return fmt.Errorf("expected object, got %T", feat.ret)
+	}
+
+	return nil
+}
+
 func InitializeScenario(s *godog.ScenarioContext) {
 	feat := RubyFeature{
 		mrb: mruby.New(),
@@ -107,6 +116,7 @@ func InitializeScenario(s *godog.ScenarioContext) {
 	s.Step(`^there should return nil$`, feat.thereShouldReturnNil)
 	s.Step(`^there should return string "([^"]*)"$`, feat.thereShouldReturnString)
 	s.Step(`^there should return symbol "([^"]*)"$`, feat.thereShouldReturnSymbol)
+	s.Step(`^there should return object$`, feat.thereShouldReturnObject)
 }
 
 func TestFeatures(t *testing.T) {
diff --git a/features/object.feature b/features/object.feature
new file mode 100644
index 0000000..f5e49a9
--- /dev/null
+++ b/features/object.feature
@@ -0,0 +1,21 @@
+Feature: Object
+  Scenario: I can get Object class
+    When I execute ruby code:
+      """
+      Object
+      """
+    Then there should return object
+
+  Scenario: I can get Module class
+    When I execute ruby code:
+      """
+      Module
+      """
+    Then there should return object
+
+  Scenario: I can get Class class
+    When I execute ruby code:
+      """
+      Class
+      """
+    Then there should return object
diff --git a/object.go b/object.go
index cea0523..f59f24a 100644
--- a/object.go
+++ b/object.go
@@ -2,12 +2,22 @@ package mruby
 
 import "fmt"
 
-type RBasic struct {
+type object struct {
 	class *RClass
 }
 
+type RBasic interface {
+	Class() *RClass
+}
+
+var _ RBasic = &RObject{}
+
 type RObject struct {
-	RBasic
+	object
+}
+
+func (obj *object) Class() *RClass {
+	return nil
 }
 
 func initObject(mrb *State) {
diff --git a/value.go b/value.go
new file mode 100644
index 0000000..7725bd3
--- /dev/null
+++ b/value.go
@@ -0,0 +1,5 @@
+package mruby
+
+func NewObjectValue(v any) Value {
+	return v.(RBasic)
+}
diff --git a/variable.go b/variable.go
index 209cfe7..f167170 100644
--- a/variable.go
+++ b/variable.go
@@ -11,6 +11,10 @@ func (iv ivTable) Set(sym Symbol, val Value) {
 	iv[sym] = val
 }
 
+func (mrb *State) DefineConstById(klass *RClass, name Symbol, val Value) {
+	klass.Set(name, val)
+}
+
 func (mrb *State) VmGetConst(sym Symbol) Value {
 	klass := mrb.ObjectClass
 	return klass.Get(sym)