diff --git a/ast.go b/ast.go
index 71079ea9..9748b965 100644
--- a/ast.go
+++ b/ast.go
@@ -714,6 +714,15 @@ retry:
 	switch t := fn.Val.(type) {
 	case *ast.BinaryExpr:
 		t.X, t.Y = checkParenExpr(args[0].Val), checkParenExpr(args[1].Val)
+		// update untyped
+		if pkg.cb.rec != nil {
+			if isBasicUntyped(args[0].Type) {
+				pkg.cb.rec.UpdateUntyped(args[0], tyRet)
+			}
+			if (t.Op != token.SHL && t.Op != token.SHR) && isBasicUntyped(args[1].Type) {
+				pkg.cb.rec.UpdateUntyped(args[1], tyRet)
+			}
+		}
 		return &internal.Elem{Val: t, Type: tyRet, CVal: cval}, nil
 	case *ast.UnaryExpr:
 		t.X = args[0].Val
@@ -741,8 +750,9 @@ func matchTypeCast(pkg *Package, typ types.Type, fn *internal.Elem, args []*inte
 		fnVal = &ast.ParenExpr{X: fnVal}
 	}
 	if len(args) == 1 && ConvertibleTo(pkg, args[0].Type, typ) {
+		// update untyped
 		if pkg.cb.rec != nil && isBasicUntyped(args[0].Type) {
-			pkg.cb.rec.UpdateType(args[0], typ)
+			pkg.cb.rec.UpdateUntyped(args[0], typ)
 		}
 		if args[0].CVal != nil {
 			if t, ok := typ.(*types.Named); ok {
@@ -1190,6 +1200,7 @@ func (p *MatchError) Error() string {
 
 // TODO: use matchType to all assignable check
 func matchType(pkg *Package, arg *internal.Elem, param types.Type, at interface{}) (r error) {
+	// update untyped
 	if pkg.cb.rec != nil && isBasicUntyped(arg.Type) {
 		defer func() {
 			if r == nil {
@@ -1200,7 +1211,7 @@ func matchType(pkg *Package, arg *internal.Elem, param types.Type, at interface{
 					typ = t.tBound
 					goto retry
 				case *types.Basic:
-					pkg.cb.rec.UpdateType(arg, t)
+					pkg.cb.rec.UpdateUntyped(arg, t)
 				}
 			}
 		}()
diff --git a/codebuild.go b/codebuild.go
index 2af7fe65..3a58b4ae 100644
--- a/codebuild.go
+++ b/codebuild.go
@@ -1075,8 +1075,9 @@ func (p *CodeBuilder) StructLit(typ types.Type, arity int, keyVal bool, src ...a
 					pos, "cannot use %s (type %v) as type %v in value of field %s",
 					src, args[i+1].Type, eltTy, eltName)
 			}
+			// update untyped
 			if pkg.cb.rec != nil && isBasicUntyped(args[i+1].Type) {
-				pkg.cb.rec.UpdateType(args[i+1], eltTy)
+				pkg.cb.rec.UpdateUntyped(args[i+1], eltTy)
 			}
 			elts[i>>1] = &ast.KeyValueExpr{Key: ident(eltName), Value: args[i+1].Val}
 		}
@@ -1100,8 +1101,9 @@ func (p *CodeBuilder) StructLit(typ types.Type, arity int, keyVal bool, src ...a
 					pos, "cannot use %s (type %v) as type %v in value of field %s",
 					src, arg.Type, eltTy, t.Field(i).Name())
 			}
+			// update untyped
 			if pkg.cb.rec != nil && isBasicUntyped(arg.Type) {
-				pkg.cb.rec.UpdateType(arg, eltTy)
+				pkg.cb.rec.UpdateUntyped(arg, eltTy)
 			}
 		}
 	}
@@ -1151,15 +1153,16 @@ func (p *CodeBuilder) Slice(slice3 bool, src ...ast.Node) *CodeBuilder { // a[i:
 	if slice3 {
 		exprMax = args[3].Val
 	}
+	// update untyped
 	if p.rec != nil {
 		if isBasicUntyped(args[1].Type) {
-			p.rec.UpdateType(args[1], types.Default(args[1].Type))
+			p.rec.UpdateUntyped(args[1], types.Default(args[1].Type))
 		}
 		if isBasicUntyped(args[2].Type) {
-			p.rec.UpdateType(args[2], types.Default(args[2].Type))
+			p.rec.UpdateUntyped(args[2], types.Default(args[2].Type))
 		}
 		if slice3 && isBasicUntyped(args[3].Type) {
-			p.rec.UpdateType(args[3], types.Default(args[3].Type))
+			p.rec.UpdateUntyped(args[3], types.Default(args[3].Type))
 		}
 	}
 
@@ -2072,6 +2075,16 @@ retry:
 		if !ComparableTo(pkg, args[0], args[1]) {
 			return nil, errors.New("mismatched types")
 		}
+		// update untyped
+		if pkg.cb.rec != nil {
+			b0 := isBasicUntyped(args[0].Type)
+			b1 := isBasicUntyped(args[1].Type)
+			if b0 && !b1 {
+				pkg.cb.rec.UpdateUntyped(args[0], args[1].Type)
+			} else if b1 && !b0 {
+				pkg.cb.rec.UpdateUntyped(args[1], args[0].Type)
+			}
+		}
 		ret = &internal.Elem{
 			Val: &ast.BinaryExpr{
 				X: checkParenExpr(args[0].Val), Op: op,
diff --git a/package.go b/package.go
index ef3aab41..b88aba01 100644
--- a/package.go
+++ b/package.go
@@ -73,7 +73,7 @@ func fatal(msg string) {
 type Recorder interface {
 	// Member maps identifiers to the objects they denote.
 	Member(id ast.Node, obj types.Object)
-	UpdateType(e *Element, typ types.Type)
+	UpdateUntyped(e *Element, typ types.Type)
 }
 
 // ----------------------------------------------------------------------------
diff --git a/package_test.go b/package_test.go
index b10031d4..e24db31c 100644
--- a/package_test.go
+++ b/package_test.go
@@ -52,6 +52,8 @@ type eventRecorder struct{}
 
 func (p eventRecorder) Member(id ast.Node, obj types.Object) {
 }
+func (p eventRecorder) UpdateUntyped(e *gox.Element, typ types.Type) {
+}
 
 func newMainPackage(
 	implicitCast ...func(pkg *gox.Package, V, T types.Type, pv *gox.Element) bool) *gox.Package {
diff --git a/template.go b/template.go
index 284b8cbe..621f2327 100644
--- a/template.go
+++ b/template.go
@@ -225,13 +225,7 @@ func DefaultConv(pkg *Package, t types.Type, pv *Element) types.Type {
 			log.Panicln("==> DefaultConv failed: overload functions have no default type")
 		}
 	default:
-		if isBasicUntyped(typ) {
-			typ := types.Default(t)
-			if pkg.cb.rec != nil && pv != nil {
-				pkg.cb.rec.UpdateType(pv, typ)
-			}
-			return typ
-		}
+		return types.Default(t)
 	}
 	return t
 }
diff --git a/type_var_and_const.go b/type_var_and_const.go
index 5ddf6538..91322176 100644
--- a/type_var_and_const.go
+++ b/type_var_and_const.go
@@ -328,8 +328,9 @@ func (p *ValueDecl) endInit(cb *CodeBuilder, arity int) *ValueDecl {
 			if err := matchType(pkg, ret, typ, "assignment"); err != nil {
 				panic(err)
 			}
+			// update untyped
 			if cb.rec != nil && isBasicUntyped(ret.Type) {
-				cb.rec.UpdateType(ret, typ)
+				cb.rec.UpdateUntyped(ret, typ)
 			}
 			if values != nil { // ret.Val may be changed
 				values[i] = ret.Val
@@ -366,8 +367,9 @@ func (p *ValueDecl) endInit(cb *CodeBuilder, arity int) *ValueDecl {
 			if values != nil {
 				values[i] = parg.Val
 			}
+			// update untyped
 			if pkg.cb.rec != nil && isBasicUntyped(rets[i].Type) {
-				pkg.cb.rec.UpdateType(rets[i], retType)
+				pkg.cb.rec.UpdateUntyped(rets[i], retType)
 			}
 			if old := p.scope.Insert(types.NewVar(p.pos, pkg.Types, name, retType)); old != nil {
 				if p.tok != token.DEFINE {