diff --git a/qmljs_environment.cpp b/qmljs_environment.cpp
index 140b5ac933..299ffffc4a 100644
--- a/qmljs_environment.cpp
+++ b/qmljs_environment.cpp
@@ -118,7 +118,7 @@ void DeclarativeEnvironment::createMutableBinding(ExecutionContext *ctx, String
     desc.configurable = deletable ? PropertyDescriptor::Set : PropertyDescriptor::Unset;
     desc.writable = PropertyDescriptor::Set;
     desc.enumberable = PropertyDescriptor::Set;
-    activation->__defineOwnProperty__(ctx, name, &desc, true);
+    activation->__defineOwnProperty__(ctx, name, &desc);
 }
 
 void DeclarativeEnvironment::setMutableBinding(String *name, Value value, bool strict)
@@ -159,9 +159,10 @@ Value DeclarativeEnvironment::getBindingValue(String *name, bool strict) const
 bool DeclarativeEnvironment::deleteBinding(ExecutionContext *ctx, String *name)
 {
     if (activation)
-        activation->__delete__(ctx, name, false);
+        activation->__delete__(ctx, name);
 
-    // ### throw in strict mode?
+    if (ctx->lexicalEnvironment->strictMode)
+        __qmljs_throw_type_error(ctx);
     return false;
 }
 
diff --git a/qmljs_objects.cpp b/qmljs_objects.cpp
index a43b576c05..35bea07f8c 100644
--- a/qmljs_objects.cpp
+++ b/qmljs_objects.cpp
@@ -165,7 +165,7 @@ bool Object::__canPut__(ExecutionContext *ctx, String *name)
 }
 
 // Section 8.12.5
-void Object::__put__(ExecutionContext *ctx, String *name, const Value &value, bool throwException)
+void Object::__put__(ExecutionContext *ctx, String *name, const Value &value)
 {
     // clause 1
     if (!__canPut__(ctx, name))
@@ -183,7 +183,7 @@ void Object::__put__(ExecutionContext *ctx, String *name, const Value &value, bo
 
             // ### to simplify and speed up we should expand the relevant parts here (clauses 6,7,9,10,12,13)
             PropertyDescriptor desc = PropertyDescriptor::fromValue(value);
-            __defineOwnProperty__(ctx, name, &desc, throwException);
+            __defineOwnProperty__(ctx, name, &desc);
             return;
         }
 
@@ -210,7 +210,7 @@ void Object::__put__(ExecutionContext *ctx, String *name, const Value &value, bo
     }
 
   reject:
-    if (throwException)
+    if (ctx->lexicalEnvironment->strictMode)
         __qmljs_throw_type_error(ctx);
 }
 
@@ -224,7 +224,7 @@ bool Object::__hasProperty__(ExecutionContext *ctx, String *name) const
 }
 
 // Section 8.12.7
-bool Object::__delete__(ExecutionContext *ctx, String *name, bool throwException)
+bool Object::__delete__(ExecutionContext *ctx, String *name)
 {
     if (members) {
         if (PropertyTableEntry *entry = members->findEntry(name)) {
@@ -232,7 +232,7 @@ bool Object::__delete__(ExecutionContext *ctx, String *name, bool throwException
                 members->remove(entry);
                 return true;
             }
-            if (throwException)
+            if (ctx->lexicalEnvironment->strictMode)
                 __qmljs_throw_type_error(ctx);
             return false;
         }
@@ -241,7 +241,7 @@ bool Object::__delete__(ExecutionContext *ctx, String *name, bool throwException
 }
 
 // Section 8.12.9
-bool Object::__defineOwnProperty__(ExecutionContext *ctx, String *name, PropertyDescriptor *desc, bool throwException)
+bool Object::__defineOwnProperty__(ExecutionContext *ctx, String *name, PropertyDescriptor *desc)
 {
     if (!members)
         members = new PropertyTable();
@@ -315,7 +315,7 @@ bool Object::__defineOwnProperty__(ExecutionContext *ctx, String *name, Property
     return true;
   reject:
     qDebug() << "___put__ rejected" << name->toQString();
-    if (throwException)
+    if (ctx->lexicalEnvironment->strictMode)
         __qmljs_throw_type_error(ctx);
     return false;
 }
diff --git a/qmljs_objects.h b/qmljs_objects.h
index 55907e10e0..45e301c56e 100644
--- a/qmljs_objects.h
+++ b/qmljs_objects.h
@@ -408,11 +408,11 @@ struct Object {
     virtual Value __get__(ExecutionContext *ctx, String *name);
     virtual PropertyDescriptor *__getOwnProperty__(ExecutionContext *ctx, String *name);
     virtual PropertyDescriptor *__getPropertyDescriptor__(ExecutionContext *ctx, String *name, PropertyDescriptor *to_fill);
-    virtual void __put__(ExecutionContext *ctx, String *name, const Value &value, bool throwException = false);
+    virtual void __put__(ExecutionContext *ctx, String *name, const Value &value);
     virtual bool __canPut__(ExecutionContext *ctx, String *name);
     virtual bool __hasProperty__(ExecutionContext *ctx, String *name) const;
-    virtual bool __delete__(ExecutionContext *ctx, String *name, bool throwException = false);
-    virtual bool __defineOwnProperty__(ExecutionContext *ctx, String *name, PropertyDescriptor *desc, bool throwException = false);
+    virtual bool __delete__(ExecutionContext *ctx, String *name);
+    virtual bool __defineOwnProperty__(ExecutionContext *ctx, String *name, PropertyDescriptor *desc);
 
     //
     // helpers
diff --git a/qmljs_runtime.cpp b/qmljs_runtime.cpp
index 7182ad07c1..a6fd7862bf 100644
--- a/qmljs_runtime.cpp
+++ b/qmljs_runtime.cpp
@@ -192,7 +192,7 @@ Value __qmljs_delete_subscript(ExecutionContext *ctx, Value base, Value index)
 Value __qmljs_delete_member(ExecutionContext *ctx, Value base, String *name)
 {
     Value obj = base.toObject(ctx);
-    return Value::fromBoolean(obj.objectValue()->__delete__(ctx, name, true));
+    return Value::fromBoolean(obj.objectValue()->__delete__(ctx, name));
 }
 
 Value __qmljs_delete_name(ExecutionContext *ctx, String *name)
@@ -543,7 +543,7 @@ Value __qmljs_new_string_object(ExecutionContext *ctx, String *string)
 
 void __qmljs_set_property(ExecutionContext *ctx, Value object, String *name, Value value)
 {
-    object.objectValue()->__put__(ctx, name, value, /*flags*/ 0);
+    object.objectValue()->__put__(ctx, name, value);
 }
 
 Value __qmljs_get_element(ExecutionContext *ctx, Value object, Value index)
@@ -583,7 +583,7 @@ void __qmljs_set_element(ExecutionContext *ctx, Value object, Value index, Value
     if (! object.isObject())
         object = __qmljs_to_object(object, ctx);
 
-    object.objectValue()->__put__(ctx, name, value, /*flags*/ 0);
+    object.objectValue()->__put__(ctx, name, value);
 }
 
 Value __qmljs_foreach_iterator_object(Value in, ExecutionContext *ctx)
diff --git a/qv4ecmaobjects.cpp b/qv4ecmaobjects.cpp
index 01c0d824fe..67ef7aa8a5 100644
--- a/qv4ecmaobjects.cpp
+++ b/qv4ecmaobjects.cpp
@@ -1414,7 +1414,7 @@ Value ArrayPrototype::method_pop(ExecutionContext *ctx)
     if (r2) {
         String *r6 = Value::fromDouble(r2 - 1).toString(ctx);
         Value r7 = self.property(ctx, r6);
-        self.objectValue()->__delete__(ctx, r6, 0);
+        self.objectValue()->__delete__(ctx, r6);
         self.objectValue()->__put__(ctx, ctx->engine->id_length, Value::fromDouble(2 - 1));
         return r7;
     }