diff --git a/objects/builtin_convert.go b/objects/builtin_convert.go
index 460a921..2dfb7e2 100644
--- a/objects/builtin_convert.go
+++ b/objects/builtin_convert.go
@@ -16,9 +16,7 @@ func builtinString(args ...Object) (Object, error) {
 	}
 
 	if argsLen == 2 {
-		if _, ok := args[1].(*String); ok {
-			return args[1], nil
-		}
+		return args[1], nil
 	}
 
 	return UndefinedValue, nil
@@ -40,9 +38,7 @@ func builtinInt(args ...Object) (Object, error) {
 	}
 
 	if argsLen == 2 {
-		if _, ok := args[1].(*Int); ok {
-			return args[1], nil
-		}
+		return args[1]
 	}
 
 	return UndefinedValue, nil
@@ -64,12 +60,7 @@ func builtinFloat(args ...Object) (Object, error) {
 	}
 
 	if argsLen == 2 {
-		if _, ok := args[1].(*Float); ok {
-			return args[1], nil
-		} else if _, ok := args[1].(*Int); ok {
-			v, _ := ToFloat64(args[1])
-			return &Float{Value: v}, nil
-		}
+		return args[1]
 	}
 
 	return UndefinedValue, nil
@@ -108,9 +99,7 @@ func builtinChar(args ...Object) (Object, error) {
 	}
 
 	if argsLen == 2 {
-		if _, ok := args[1].(*Char); ok {
-			return args[1], nil
-		}
+		return args[1]
 	}
 
 	return UndefinedValue, nil
@@ -133,15 +122,7 @@ func builtinBytes(args ...Object) (Object, error) {
 	}
 
 	if argsLen == 2 {
-		// bytes(N) => create a new bytes with given size N
-		if n, ok := args[1].(*Int); ok {
-			return &Bytes{Value: make([]byte, int(n.Value))}, nil
-		}
-	
-		v, ok = ToByteSlice(args[1])
-		if ok {
-			return &Bytes{Value: v}, nil
-		}
+		return args[1]
 	}
 
 	return UndefinedValue, nil
diff --git a/runtime/vm_builtin_test.go b/runtime/vm_builtin_test.go
index 705834d..587269e 100644
--- a/runtime/vm_builtin_test.go
+++ b/runtime/vm_builtin_test.go
@@ -29,7 +29,8 @@ func TestBuiltinFunction(t *testing.T) {
 	expect(t, `out = int(undefined)`, undefined())
 	expect(t, `out = int("-522", 1)`, -522)
 	expect(t, `out = int(undefined, 1)`, 1)
-	expect(t, `out = int(undefined, 1.8)`, undefined())
+	expect(t, `out = int(undefined, 1.8)`, 1.8)
+	expect(t, `out = int(undefined, string(1))`, "1")
 	expect(t, `out = int(undefined, undefined)`, undefined())
 
 	expect(t, `out = string(1)`, "1")
@@ -54,9 +55,10 @@ func TestBuiltinFunction(t *testing.T) {
 	expect(t, `out = float({a: 1, b: "foo"})`, undefined())
 	expect(t, `out = float(undefined)`, undefined())
 	expect(t, `out = float("-52.2", 1.8)`, -52.2)
-	expect(t, `out = float(undefined, 1)`, 1.0)
+	expect(t, `out = float(undefined, 1)`, 1)
 	expect(t, `out = float(undefined, 1.8)`, 1.8)
-	expect(t, `out = float(undefined, "-52.2")`, undefined())
+	expect(t, `out = float(undefined, "-52.2")`, "-52.2")
+	expect(t, `out = float(undefined, char(56))`, '8')
 	expect(t, `out = float(undefined, undefined)`, undefined())
 
 	expect(t, `out = char(56)`, '8')
@@ -70,8 +72,9 @@ func TestBuiltinFunction(t *testing.T) {
 	expect(t, `out = char(undefined)`, undefined())
 	expect(t, `out = char(56, 'a')`, '8')
 	expect(t, `out = char(undefined, '8')`, '8')
-	expect(t, `out = char(undefined, 56)`, undefined())
-	expect(t, `out = char(undefined, "-52.2")`, undefined())
+	expect(t, `out = char(undefined, 56)`, 56)
+	expect(t, `out = char(undefined, "-52.2")`, "-52.2")
+	expect(t, `out = char(undefined, undefined)`, undefined())
 
 	expect(t, `out = bool(1)`, true)          // non-zero integer: true
 	expect(t, `out = bool(0)`, false)         // zero: true
@@ -99,9 +102,10 @@ func TestBuiltinFunction(t *testing.T) {
 	expect(t, `out = bytes({a: 1})`, undefined())
 	expect(t, `out = bytes(undefined)`, undefined())
 	expect(t, `out = bytes("-522", ['8'])`, []byte{'-', '5', '2', '2'})
-	expect(t, `out = bytes(undefined, "-522")`, []byte{'-', '5', '2', '2'})
-	expect(t, `out = bytes(undefined, 1)`, []byte{0})
-	expect(t, `out = bytes(undefined, 1.8)`, undefined())
+	expect(t, `out = bytes(undefined, "-522")`, "-522")
+	expect(t, `out = bytes(undefined, 1)`, 1)
+	expect(t, `out = bytes(undefined, 1.8)`, 1.8)
+	expect(t, `out = bytes(undefined, int("-522"))`, -522)
 	expect(t, `out = bytes(undefined, undefined)`, undefined())
 
 	expect(t, `out = is_error(error(1))`, true)