diff --git a/_integration_tests/integration_test.go b/_integration_tests/integration_test.go
index 89359605..bab23049 100644
--- a/_integration_tests/integration_test.go
+++ b/_integration_tests/integration_test.go
@@ -167,6 +167,49 @@ func TestIssue161(t *testing.T) {
 	}
 }
 
+func TestIssue301(t *testing.T) {
+	defer cleanup("./issue301/*")
+	if err := goagen("./issue301", "bootstrap", "-d", "github.com/shogo82148/goa-v1/_integration_tests/issue301/design"); err != nil {
+		t.Error(err.Error())
+	}
+	if err := gobuild("./issue301"); err != nil {
+		t.Error(err.Error())
+	}
+	b, err := os.ReadFile("./issue301/app/user_types.go")
+	if err != nil {
+		t.Fatal("failed to load user_types.go")
+	}
+
+	// include user definition type: "github.com/shogo82148/goa-v1/design"
+	expectedImport := `import (
+	goa "github.com/shogo82148/goa-v1"
+	"github.com/shogo82148/goa-v1/design"
+	"time"
+)`
+
+	expectedFinalize := `func (ut *issue301Type) Finalize() {
+	var defaultPrimitiveTypeNumber float64 = 3.140000
+	if ut.PrimitiveTypeNumber == nil {
+		ut.PrimitiveTypeNumber = &defaultPrimitiveTypeNumber
+	}
+	var defaultPrimitiveTypeTime, _ = time.Parse(time.RFC3339, "2006-01-02T15:04:05Z")
+	if ut.PrimitiveTypeTime == nil {
+		ut.PrimitiveTypeTime = &defaultPrimitiveTypeTime
+	}
+	var defaultUserDefinitionType design.SecuritySchemeKind = 10
+	if ut.UserDefinitionType == nil {
+		ut.UserDefinitionType = &defaultUserDefinitionType
+	}
+}`
+	if !strings.Contains(string(b), expectedImport) {
+		t.Errorf("Failed to generate 'import' block code that sets default values for user-defined types. Generated context:\n%s", string(b))
+	}
+
+	if !strings.Contains(string(b), expectedFinalize) {
+		t.Errorf("Failed to generate 'Finalize' function code that sets default values for user-defined types. Generated context:\n%s", string(b))
+	}
+}
+
 func goagen(dir, command string, args ...string) error {
 	pkg, err := build.Import("github.com/shogo82148/goa-v1/goagen", "", 0)
 	if err != nil {
diff --git a/_integration_tests/issue301/design/design.go b/_integration_tests/issue301/design/design.go
new file mode 100644
index 00000000..7ce7f1b6
--- /dev/null
+++ b/_integration_tests/issue301/design/design.go
@@ -0,0 +1,39 @@
+package design
+
+import (
+	. "github.com/shogo82148/goa-v1/design"
+	. "github.com/shogo82148/goa-v1/design/apidsl"
+)
+
+var _ = API("issue301", func() {
+	Title("This API has user definition type default values")
+	Host("localhost:8080")
+	Scheme("https")
+})
+
+var _ = Resource("issue301", func() {
+	Action("test", func() {
+		Routing(GET("user-definition"))
+		Payload(Issue301Payload)
+		Response(OK)
+	})
+})
+
+var Issue301Payload = Type("Issue301Type", func() {
+	Attribute("user-definition-type", Integer, func() {
+		Default(10)
+		Metadata("struct:field:type", "design.SecuritySchemeKind", "github.com/shogo82148/goa-v1/design")
+	})
+
+	Attribute("primitive-type-number", Number, func() {
+		Default(3.14)
+	})
+
+	Attribute("primitive-type-time", DateTime, func() {
+		Default("2006-01-02T15:04:05Z")
+	})
+
+	Required("user-definition-type")
+	Required("primitive-type-number")
+	Required("primitive-type-time")
+})
diff --git a/goagen/codegen/finalizer.go b/goagen/codegen/finalizer.go
index 05aa65ee..c44ac1a1 100644
--- a/goagen/codegen/finalizer.go
+++ b/goagen/codegen/finalizer.go
@@ -25,6 +25,7 @@ func NewFinalizer() *Finalizer {
 		"tabs":         Tabs,
 		"goify":        Goify,
 		"gotyperef":    GoTypeRef,
+		"gotypedef":    GoTypeDef,
 		"add":          Add,
 		"finalizeCode": f.Code,
 	}
@@ -163,7 +164,7 @@ func PrintVal(t design.DataType, val interface{}) string {
 
 const (
 	assignmentTmpl = `{{ if .catt.Type.IsPrimitive }}{{ $defaultName := (print "default" (goify .field true)) }}{{/*
-*/}}{{ tabs .depth }}var {{ $defaultName }}{{if .isDatetime}}, _{{end}} = {{ .defaultVal }}
+*/}}{{ tabs .depth }}{{if .isDatetime}}var {{ $defaultName }}, _ = {{ .defaultVal }}{{ else }}var {{ $defaultName }} {{ gotypedef .catt 0 false false }} = {{ .defaultVal }}{{end}}
 {{ tabs .depth }}if {{ .target }}.{{ goify .field true }} == nil {
 {{ tabs .depth }}	{{ .target }}.{{ goify .field true }} = &{{ $defaultName }}
 }{{ else }}{{ tabs .depth }}if {{ .target }}.{{ goify .field true }} == nil {
diff --git a/goagen/codegen/finalizer_test.go b/goagen/codegen/finalizer_test.go
index 54f95eec..ae17ce7d 100644
--- a/goagen/codegen/finalizer_test.go
+++ b/goagen/codegen/finalizer_test.go
@@ -4,6 +4,7 @@ import (
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"github.com/shogo82148/goa-v1/design"
+	"github.com/shogo82148/goa-v1/dslengine"
 	"github.com/shogo82148/goa-v1/goagen/codegen"
 )
 
@@ -160,20 +161,44 @@ var _ = Describe("Struct finalize code generation", func() {
 			Ω(code).Should(Equal(recursiveAssignmentCodeB))
 		})
 	})
+
+	Context("given an object with a user definition type", func() {
+		BeforeEach(func() {
+			att = &design.AttributeDefinition{
+				Type: &design.Object{
+					"foo": &design.AttributeDefinition{
+						Type: design.String,
+						Metadata: dslengine.MetadataDefinition{
+							"struct:field:type": []string{"UserDefinitionType", "github.com/shogo82148/goa-v1/goagen/codegen_test"},
+						},
+						DefaultValue: UserDefinitionType("bar"),
+					},
+				},
+			}
+			target = "ut"
+		})
+		It("finalizes the fields", func() {
+			code := finalizer.Code(att, target, 0)
+			Ω(code).Should(Equal(userTypeAssignmentCode))
+		})
+	})
 })
 
+// UserDefinitionType is a user defined type used in the unit tests.
+type UserDefinitionType string
+
 const (
-	primitiveAssignmentCode = `var defaultFoo = "bar"
+	primitiveAssignmentCode = `var defaultFoo string = "bar"
 if ut.Foo == nil {
 	ut.Foo = &defaultFoo
 }`
 
-	numberAssignmentCodeIntDefault = `var defaultFoo = 50.000000
+	numberAssignmentCodeIntDefault = `var defaultFoo float64 = 50.000000
 if ut.Foo == nil {
 	ut.Foo = &defaultFoo
 }`
 
-	numberAssignmentCode = `var defaultFoo = 0.000000
+	numberAssignmentCode = `var defaultFoo float64 = 0.000000
 if ut.Foo == nil {
 	ut.Foo = &defaultFoo
 }`
@@ -192,13 +217,18 @@ if ut.Foo == nil {
 }`
 
 	recursiveAssignmentCodeB = `	for _, e := range ut.Elems {
-		var defaultOther = "foo"
+		var defaultOther string = "foo"
 		if e.Other == nil {
 			e.Other = &defaultOther
 }
 	}
-var defaultOther = "foo"
+var defaultOther string = "foo"
 if ut.Other == nil {
 	ut.Other = &defaultOther
 }`
+
+	userTypeAssignmentCode = `var defaultFoo UserDefinitionType = "bar"
+if ut.Foo == nil {
+	ut.Foo = &defaultFoo
+}`
 )