diff --git a/evaluate_expression.go b/evaluate_expression.go
index f59a1b1..29882da 100644
--- a/evaluate_expression.go
+++ b/evaluate_expression.go
@@ -103,6 +103,10 @@ func (self *_runtime) evaluateUnaryOperation(node *_unaryOperationNode) Value {
 	case "void":
 		return UndefinedValue()
 	case "delete":
+		reference := target.reference()
+		if reference == nil {
+			return TrueValue()
+		}
 		return toValue(target.reference().Delete())
 	case "typeof":
 		switch targetValue._valueType {
diff --git a/otto_test.go b/otto_test.go
index b5fe65a..4782c29 100644
--- a/otto_test.go
+++ b/otto_test.go
@@ -2163,3 +2163,13 @@ func Test_stringToFloat(t *testing.T) {
 	Is(stringToFloat("10e10000"), math.Inf(1))
 	Is(stringToFloat("10e10_."), "NaN")
 }
+
+func Test_delete(t *testing.T) {
+	Terst(t)
+
+	test := runTest()
+
+	test(`
+		delete 42;
+	`, "true")
+}
diff --git a/type_reference.go b/type_reference.go
index 6938fa9..6783613 100644
--- a/type_reference.go
+++ b/type_reference.go
@@ -2,6 +2,7 @@ package otto
 
 type _reference interface {
 	GetBase() *_object
+	CanResolve() bool
 	GetValue() Value
 	PutValue(Value) bool
 	Name() string
@@ -16,10 +17,6 @@ type _reference_ struct {
 	strict bool
 }
 
-func (self _reference_) GetBase() *_object {
-	return nil
-}
-
 func (self _reference_) Name() string {
 	return self.name
 }
@@ -28,10 +25,6 @@ func (self _reference_) Strict() bool {
 	return self.strict
 }
 
-func (self _reference_) Delete() {
-	panic(hereBeDragons())
-}
-
 // PropertyReference
 
 type _propertyReference struct {
@@ -55,6 +48,10 @@ func (self *_propertyReference) GetBase() *_object {
 	return self.Base
 }
 
+func (self *_propertyReference) CanResolve() bool {
+	return self.Base != nil
+}
+
 func (self *_propertyReference) GetValue() Value {
 	if self.Base == nil {
 		panic(newReferenceError("notDefined", self.name, self.node))
@@ -73,7 +70,8 @@ func (self *_propertyReference) PutValue(value Value) bool {
 func (self *_propertyReference) Delete() bool {
 	if self.Base == nil {
 		// ?
-		return false
+		// TODO Throw an error if strict
+		return true
 	}
 	return self.Base.delete(self.name, self.Strict())
 }
@@ -108,6 +106,10 @@ func (self *_environmentReference) GetBase() *_object {
 	return nil // FIXME
 }
 
+func (self *_environmentReference) CanResolve() bool {
+	return true // FIXME
+}
+
 func (self *_environmentReference) GetValue() Value {
 	if self.Base == nil {
 		panic(newReferenceError("notDefined", self.name, self.node))