diff --git a/rendering/named_type.go b/rendering/named_type.go
index ece6c90..1b2e404 100644
--- a/rendering/named_type.go
+++ b/rendering/named_type.go
@@ -17,6 +17,13 @@ func NewNamedType(name string, t Type) NamedType {
 	}
 }
 
+func NewDefinedType(name string) NamedType {
+	return NamedType{
+		Name: name,
+		Type: Interface{},
+	}
+}
+
 func (nt NamedType) Expr() ast.Expr {
 	return ast.NewIdent(nt.Name)
 }
diff --git a/rendering/type.go b/rendering/type.go
index 1100fac..89a1873 100644
--- a/rendering/type.go
+++ b/rendering/type.go
@@ -27,7 +27,7 @@ func NewType(t types.Type) Type {
 			name = fmt.Sprintf("%s.%s", pkg.Name(), obj.Name())
 		}
 
-		return NewNamedType(name, NewType(t.Underlying()))
+		return NewDefinedType(name)
 
 	case *types.Interface:
 		return Interface{}