diff --git a/parser/interface.go b/parser/interface.go
index c4bf7c9e0..a0fd6bffd 100644
--- a/parser/interface.go
+++ b/parser/interface.go
@@ -42,9 +42,8 @@ const (
 	DeclarationErrors
 	// AllErrors - report all errors (not just the first 10 on different lines)
 	AllErrors
-	// ParseGoFilesByGo - parse Go files by go/parser, not gop/parser
-	// Result will save to gop/ast.Package.GoFiles
-	ParseGoFilesByGo
+	// ParseGoAsGoPlus - parse Go files by gop/parser
+	ParseGoAsGoPlus
 )
 
 // ParseFile parses the source code of a single Go source file and returns
diff --git a/parser/parser_gop.go b/parser/parser_gop.go
index 1bb39699c..5b80f460b 100644
--- a/parser/parser_gop.go
+++ b/parser/parser_gop.go
@@ -151,7 +151,7 @@ func ParseFSDir(fset *token.FileSet, fs FileSystem, path string, conf Config) (p
 			if strings.HasPrefix(fname, "gop_autogen") {
 				continue
 			}
-			useGoParser = (conf.Mode & ParseGoFilesByGo) != 0
+			useGoParser = (conf.Mode & ParseGoAsGoPlus) == 0
 		default:
 			if isProj, isClass = conf.IsClass(ext); !isClass {
 				continue
@@ -161,7 +161,7 @@ func ParseFSDir(fset *token.FileSet, fs FileSystem, path string, conf Config) (p
 			filename := fs.Join(path, fname)
 			if useGoParser {
 				if filedata, err := fs.ReadFile(filename); err == nil {
-					if src, err := goparser.ParseFile(fset, filename, filedata, goparser.Mode(conf.Mode & ^ParseGoFilesByGo)); err == nil {
+					if src, err := goparser.ParseFile(fset, filename, filedata, goparser.Mode(conf.Mode)); err == nil {
 						pkg := reqPkg(pkgs, src.Name.Name)
 						if pkg.GoFiles == nil {
 							pkg.GoFiles = make(map[string]*goast.File)
diff --git a/parser/parserdir_test.go b/parser/parserdir_test.go
index 503cb29c6..9fb0aa53a 100644
--- a/parser/parserdir_test.go
+++ b/parser/parserdir_test.go
@@ -90,7 +90,7 @@ func testFrom(t *testing.T, pkgDir, sel string, exclude Mode) {
 	}
 	log.Println("Parsing", pkgDir)
 	fset := token.NewFileSet()
-	pkgs, err := ParseDir(fset, pkgDir, nil, (Trace|ParseComments)&^exclude)
+	pkgs, err := ParseDir(fset, pkgDir, nil, (Trace|ParseComments|ParseGoAsGoPlus)&^exclude)
 	if err != nil || len(pkgs) != 1 {
 		if errs, ok := err.(scanner.ErrorList); ok {
 			for _, e := range errs {
@@ -111,7 +111,7 @@ func testFrom(t *testing.T, pkgDir, sel string, exclude Mode) {
 
 func TestParseGo(t *testing.T) {
 	fset := token.NewFileSet()
-	pkgs, err := ParseDirEx(fset, "./_testdata/functype", Config{Mode: Trace})
+	pkgs, err := ParseDirEx(fset, "./_testdata/functype", Config{Mode: Trace | ParseGoAsGoPlus})
 	if err != nil {
 		t.Fatal("TestParseGo: ParseDir failed -", err)
 	}
@@ -122,7 +122,7 @@ func TestParseGo(t *testing.T) {
 
 func TestParseGoFiles(t *testing.T) {
 	fset := token.NewFileSet()
-	pkgs, err := ParseFiles(fset, []string{"./_testdata/functype/functype.go"}, Trace)
+	pkgs, err := ParseFiles(fset, []string{"./_testdata/functype/functype.go"}, Trace|ParseGoAsGoPlus)
 	if err != nil {
 		t.Fatal("TestParseGoFiles: ParseFiles failed -", err)
 	}
@@ -146,7 +146,7 @@ func TestGopAutoGen(t *testing.T) {
 func TestGoFile(t *testing.T) {
 	fset := token.NewFileSet()
 	fs := parsertest.NewSingleFileFS("/foo", "test.go", `package foo`)
-	pkgs, err := ParseFSDir(fset, fs, "/foo", Config{Mode: ParseGoFilesByGo})
+	pkgs, err := ParseFSDir(fset, fs, "/foo", Config{})
 	if err != nil {
 		t.Fatal("ParseFSDir:", err)
 	}
@@ -158,19 +158,19 @@ func TestGoFile(t *testing.T) {
 func TestErrParse(t *testing.T) {
 	fset := token.NewFileSet()
 	fs := parsertest.NewSingleFileFS("/foo", "test.go", `package foo bar`)
-	_, err := ParseFSDir(fset, fs, "/foo", Config{Mode: ParseGoFilesByGo})
+	_, err := ParseFSDir(fset, fs, "/foo", Config{})
 	if err == nil {
 		t.Fatal("ParseFSDir test.go: no error?")
 	}
 
 	fs = parsertest.NewSingleFileFS("/foo", "test.gop", `package foo bar`)
-	_, err = ParseFSDir(fset, fs, "/foo", Config{Mode: ParseGoFilesByGo})
+	_, err = ParseFSDir(fset, fs, "/foo", Config{})
 	if err == nil {
 		t.Fatal("ParseFSDir test.gop: no error?")
 	}
 
 	fs = parsertest.NewMemFS(map[string][]string{"/foo": {"test.go"}}, map[string]string{})
-	_, err = ParseFSDir(fset, fs, "/foo", Config{Mode: ParseGoFilesByGo})
+	_, err = ParseFSDir(fset, fs, "/foo", Config{})
 	if err != syscall.ENOENT {
 		t.Fatal("ParseFSDir:", err)
 	}