diff --git a/src/libtiled/map.cpp b/src/libtiled/map.cpp
index b9e20271a7..98889dca26 100644
--- a/src/libtiled/map.cpp
+++ b/src/libtiled/map.cpp
@@ -52,7 +52,7 @@ Map::Map(Orientation orientation,
     mStaggerAxis(StaggerY),
     mStaggerIndex(StaggerOdd),
     mLayerDataFormat(Base64Zlib),
-    mNextUid(0)
+    mNextObjectId(1)
 {
 }
 
@@ -71,7 +71,7 @@ Map::Map(const Map &map):
     mDrawMargins(map.mDrawMargins),
     mTilesets(map.mTilesets),
     mLayerDataFormat(map.mLayerDataFormat),
-    mNextUid(0)
+    mNextObjectId(1)
 {
     foreach (const Layer *layer, map.mLayers) {
         Layer *clone = layer->clone();
@@ -188,8 +188,8 @@ void Map::adoptLayer(Layer *layer)
 
     if (ObjectGroup *group = layer->asObjectGroup()) {
         foreach (MapObject *o, group->objects()) {
-            if (o->uniqueID() == -1)
-                o->setUniqueID(nextUid());
+            if (o->id() == 0)
+                o->setId(takeNextObjectId());
         }
     }
 }
diff --git a/src/libtiled/map.h b/src/libtiled/map.h
index bb51bbb240..d14767bdc5 100644
--- a/src/libtiled/map.h
+++ b/src/libtiled/map.h
@@ -370,23 +370,23 @@ class TILEDSHARED_EXPORT Map : public Object
     { mLayerDataFormat = format; }
 
     /**
-     * Sets the next UniqueId of this map.
+     * Sets the next id to be used for objects on this map.
      */
-    void setNextUid(int nextUid) {
-        if (nextUid == 0)
-            nextUid = 1;
-        mNextUid = nextUid;
+    void setNextObjectId(int nextId)
+    {
+        Q_ASSERT(nextId > 0);
+        mNextObjectId = nextId;
     }
 
     /**
-     * Returns the next UniqueId for this map.
+     * Returns the next object id for this map.
      */
-    int nextUid() { return mNextUid++; }
+    int nextObjectId() const { return mNextObjectId; }
 
     /**
-     * Returns the current UniqueId for this map.
+     * Returns the next object id for this map and allocates a new one.
      */
-    int currentNextUid() const { return  mNextUid; }
+    int takeNextObjectId() { return mNextObjectId++; }
 
 private:
     void adoptLayer(Layer *layer);
@@ -405,8 +405,7 @@ class TILEDSHARED_EXPORT Map : public Object
     QList<Layer*> mLayers;
     QList<Tileset*> mTilesets;
     LayerDataFormat mLayerDataFormat;
-
-    int mNextUid;
+    int mNextObjectId;
 };
 
 
diff --git a/src/libtiled/mapobject.cpp b/src/libtiled/mapobject.cpp
index 8ec8ada205..f7046803e5 100644
--- a/src/libtiled/mapobject.cpp
+++ b/src/libtiled/mapobject.cpp
@@ -33,12 +33,12 @@ using namespace Tiled;
 
 MapObject::MapObject():
     Object(MapObjectType),
+    mId(0),
     mSize(0, 0),
     mShape(Rectangle),
     mObjectGroup(0),
     mRotation(0.0f),
-    mVisible(true),
-    mUniqueID(-1)
+    mVisible(true)
 {
 }
 
@@ -46,6 +46,7 @@ MapObject::MapObject(const QString &name, const QString &type,
                      const QPointF &pos,
                      const QSizeF &size):
     Object(MapObjectType),
+    mId(0),
     mName(name),
     mType(type),
     mPos(pos),
@@ -53,8 +54,7 @@ MapObject::MapObject(const QString &name, const QString &type,
     mShape(Rectangle),
     mObjectGroup(0),
     mRotation(0.0f),
-    mVisible(true),
-    mUniqueID(-1)
+    mVisible(true)
 {
 }
 
diff --git a/src/libtiled/mapobject.h b/src/libtiled/mapobject.h
index fea84fa987..1f1ff8c25a 100644
--- a/src/libtiled/mapobject.h
+++ b/src/libtiled/mapobject.h
@@ -76,14 +76,15 @@ class TILEDSHARED_EXPORT MapObject : public Object
               const QSizeF &size);
 
     /**
-     * Returns the unique id of this object.
+     * Returns the id of this object. Each object gets an id assigned that is
+     * unique for the map the object is on.
      */
-    int uniqueID() const { return mUniqueID; }
+    int id() const { return mId; }
 
     /**
-     * Sets the unique id of this object.
+     * Sets the id of this object.
      */
-    void setUniqueID(int id) { mUniqueID = id; }
+    void setId(int id) { mId = id; }
 
     /**
      * Returns the name of this object. The name is usually just used for
@@ -250,6 +251,7 @@ class TILEDSHARED_EXPORT MapObject : public Object
     MapObject *clone() const;
 
 private:
+    int mId;
     QString mName;
     QString mType;
     QPointF mPos;
@@ -260,7 +262,6 @@ class TILEDSHARED_EXPORT MapObject : public Object
     ObjectGroup *mObjectGroup;
     qreal mRotation;
     bool mVisible;
-    int mUniqueID;
 };
 
 } // namespace Tiled
diff --git a/src/libtiled/mapreader.cpp b/src/libtiled/mapreader.cpp
index 41e4016085..c5c68e87c3 100644
--- a/src/libtiled/mapreader.cpp
+++ b/src/libtiled/mapreader.cpp
@@ -238,15 +238,16 @@ Map *MapReaderPrivate::readMap()
     const Map::RenderOrder renderOrder =
             renderOrderFromString(renderOrderString);
 
-    const int nextUid =
-            atts.value(QLatin1String("nextUid")).toString().toInt();
+    const int nextObjectId =
+            atts.value(QLatin1String("nextobjectid")).toString().toInt();
 
     mMap = new Map(orientation, mapWidth, mapHeight, tileWidth, tileHeight);
     mMap->setHexSideLength(hexSideLength);
     mMap->setStaggerAxis(staggerAxis);
     mMap->setStaggerIndex(staggerIndex);
     mMap->setRenderOrder(renderOrder);
-    mMap->setNextUid(nextUid);
+    if (nextObjectId)
+        mMap->setNextObjectId(nextObjectId);
 
     mCreatedTilesets.clear();
 
@@ -825,7 +826,7 @@ MapObject *MapReaderPrivate::readObject()
     Q_ASSERT(xml.isStartElement() && xml.name() == QLatin1String("object"));
 
     const QXmlStreamAttributes atts = xml.attributes();
-    int uniqueID = atts.value(QLatin1String("uid")).toString().toInt();
+    const int id = atts.value(QLatin1String("id")).toString().toInt();
     const QString name = atts.value(QLatin1String("name")).toString();
     const unsigned gid = atts.value(QLatin1String("gid")).toString().toUInt();
     const qreal x = atts.value(QLatin1String("x")).toString().toDouble();
@@ -838,15 +839,8 @@ MapObject *MapReaderPrivate::readObject()
     const QPointF pos(x, y);
     const QSizeF size(width, height);
 
-    //If the uniqueID is 0, this must be an old map and this object
-    //has no UniqueID yet.  So we create it a UniqueID here.
-    if(uniqueID == 0)
-    {
-        uniqueID = mMap->nextUid();
-    }
-
     MapObject *object = new MapObject(name, type, pos, size);
-    object->setUniqueID(uniqueID);
+    object->setId(id);
 
     bool ok;
     const qreal rotation = atts.value(QLatin1String("rotation")).toString().toDouble(&ok);
diff --git a/src/libtiled/mapwriter.cpp b/src/libtiled/mapwriter.cpp
index 5887c44d84..dfc194f66d 100644
--- a/src/libtiled/mapwriter.cpp
+++ b/src/libtiled/mapwriter.cpp
@@ -200,9 +200,8 @@ void MapWriterPrivate::writeMap(QXmlStreamWriter &w, const Map *map)
                          map->backgroundColor().name());
     }
 
-    int nextUid = map->currentNextUid();
-    w.writeAttribute(QLatin1String("nextUid"),
-                     QString::number(nextUid));
+    w.writeAttribute(QLatin1String("nextobjectid"),
+                     QString::number(map->nextObjectId()));
 
     writeProperties(w, map->properties());
 
@@ -530,15 +529,13 @@ void MapWriterPrivate::writeObject(QXmlStreamWriter &w,
                                    const MapObject *mapObject)
 {
     w.writeStartElement(QLatin1String("object"));
+    w.writeAttribute(QLatin1String("id"), QString::number(mapObject->id()));
     const QString &name = mapObject->name();
     const QString &type = mapObject->type();
-    const int &uniqueID = mapObject->uniqueID();
     if (!name.isEmpty())
         w.writeAttribute(QLatin1String("name"), name);
     if (!type.isEmpty())
         w.writeAttribute(QLatin1String("type"), type);
-    if (uniqueID != 0)
-        w.writeAttribute(QLatin1String("uid"), QString::number(uniqueID));
 
     if (!mapObject->cell().isEmpty()) {
         const unsigned gid = mGidMapper.cellToGid(mapObject->cell());
diff --git a/src/libtiled/objectgroup.cpp b/src/libtiled/objectgroup.cpp
index 0a6de0f767..bb78627c47 100644
--- a/src/libtiled/objectgroup.cpp
+++ b/src/libtiled/objectgroup.cpp
@@ -62,16 +62,16 @@ void ObjectGroup::addObject(MapObject *object)
 {
     mObjects.append(object);
     object->setObjectGroup(this);
-    if (mMap && object->uniqueID() == -1)
-        object->setUniqueID(mMap->nextUid());
+    if (mMap && object->id() == 0)
+        object->setId(mMap->takeNextObjectId());
 }
 
 void ObjectGroup::insertObject(int index, MapObject *object)
 {
     mObjects.insert(index, object);
     object->setObjectGroup(this);
-    if (mMap && object->uniqueID() == -1)
-        object->setUniqueID(mMap->nextUid());
+    if (mMap && object->id() == 0)
+        object->setId(mMap->takeNextObjectId());
 }
 
 int ObjectGroup::removeObject(MapObject *object)
diff --git a/src/plugins/json/maptovariantconverter.cpp b/src/plugins/json/maptovariantconverter.cpp
index dfb2f66da2..d5332e993a 100644
--- a/src/plugins/json/maptovariantconverter.cpp
+++ b/src/plugins/json/maptovariantconverter.cpp
@@ -49,7 +49,7 @@ QVariant MapToVariantConverter::toVariant(const Map *map, const QDir &mapDir)
     mapVariant["tilewidth"] = map->tileWidth();
     mapVariant["tileheight"] = map->tileHeight();
     mapVariant["properties"] = toVariant(map->properties());
-    mapVariant["nextUid"] = map->currentNextUid();
+    mapVariant["nextobjectid"] = map->nextObjectId();
 
     if (map->orientation() == Map::Hexagonal) {
         mapVariant["hexsidelength"] = map->hexSideLength();
@@ -236,6 +236,7 @@ QVariant MapToVariantConverter::toVariant(const ObjectGroup *objectGroup) const
         const QString &type = object->type();
 
         objectVariant["properties"] = toVariant(object->properties());
+        objectVariant["id"] = object->id();
         objectVariant["name"] = name;
         objectVariant["type"] = type;
         if (!object->cell().isEmpty())
@@ -246,7 +247,6 @@ QVariant MapToVariantConverter::toVariant(const ObjectGroup *objectGroup) const
         objectVariant["width"] = object->width();
         objectVariant["height"] = object->height();
         objectVariant["rotation"] = object->rotation();
-        objectVariant["uid"] = object->uniqueID();
 
         objectVariant["visible"] = object->isVisible();
 
diff --git a/src/plugins/json/varianttomapconverter.cpp b/src/plugins/json/varianttomapconverter.cpp
index 8ee7fe909f..b54c56d695 100644
--- a/src/plugins/json/varianttomapconverter.cpp
+++ b/src/plugins/json/varianttomapconverter.cpp
@@ -69,7 +69,7 @@ Map *VariantToMapConverter::toMap(const QVariant &variant,
     const QString renderOrderString = variantMap["renderorder"].toString();
     Map::RenderOrder renderOrder = renderOrderFromString(renderOrderString);
 
-    int nextUid = variantMap["nextUid"].toString().toInt();
+    const int nextObjectId = variantMap["nextobjectid"].toString().toInt();
 
     typedef QScopedPointer<Map> MapPtr;
     MapPtr map(new Map(orientation,
@@ -81,7 +81,8 @@ Map *VariantToMapConverter::toMap(const QVariant &variant,
     map->setStaggerAxis(staggerAxis);
     map->setStaggerIndex(staggerIndex);
     map->setRenderOrder(renderOrder);
-    map->setNextUid(nextUid);
+    if (nextObjectId)
+        map->setNextObjectId(nextObjectId);
 
     mMap = map.data();
     map->setProperties(toProperties(variantMap["properties"]));
@@ -351,7 +352,7 @@ ObjectGroup *VariantToMapConverter::toObjectGroup(const QVariantMap &variantMap)
 
         const QString name = objectVariantMap["name"].toString();
         const QString type = objectVariantMap["type"].toString();
-        int uniqueID = objectVariantMap["uid"].toString().toInt();
+        const int id = objectVariantMap["id"].toString().toInt();
         const int gid = objectVariantMap["gid"].toInt();
         const qreal x = objectVariantMap["x"].toReal();
         const qreal y = objectVariantMap["y"].toReal();
@@ -362,16 +363,8 @@ ObjectGroup *VariantToMapConverter::toObjectGroup(const QVariantMap &variantMap)
         const QPointF pos(x, y);
         const QSizeF size(width, height);
 
-
-        //If the uniqueID is 0, this must be an old map and this object
-        //has no UniqueID yet.  So we create it a UniqueID here.
-        if(uniqueID == 0)
-        {
-            uniqueID = mMap->nextUid();
-        }
-
         MapObject *object = new MapObject(name, type, pos, size);
-        object->setUniqueID(uniqueID);
+        object->setId(id);
         object->setRotation(rotation);
 
         if (gid) {
diff --git a/src/plugins/lua/luaplugin.cpp b/src/plugins/lua/luaplugin.cpp
index 13e8b0d72e..23551ae42e 100644
--- a/src/plugins/lua/luaplugin.cpp
+++ b/src/plugins/lua/luaplugin.cpp
@@ -115,7 +115,7 @@ void LuaPlugin::writeMap(LuaTableWriter &writer, const Map *map)
     writer.writeKeyAndValue("height", map->height());
     writer.writeKeyAndValue("tilewidth", map->tileWidth());
     writer.writeKeyAndValue("tileheight", map->tileHeight());
-    writer.writeKeyAndValue("nextUid", map->currentNextUid());
+    writer.writeKeyAndValue("nextobjectid", map->nextObjectId());
 
     const QColor &backgroundColor = map->backgroundColor();
     if (backgroundColor.isValid()) {
@@ -405,7 +405,7 @@ void LuaPlugin::writeMapObject(LuaTableWriter &writer,
                                const Tiled::MapObject *mapObject)
 {
     writer.writeStartTable();
-    writer.writeKeyAndValue("uid", mapObject->uniqueID());
+    writer.writeKeyAndValue("id", mapObject->id());
     writer.writeKeyAndValue("name", mapObject->name());
     writer.writeKeyAndValue("type", mapObject->type());
     writer.writeKeyAndValue("shape", toString(mapObject->shape()));
diff --git a/src/tiled/propertybrowser.cpp b/src/tiled/propertybrowser.cpp
index 6b88ba8ff7..6fd31b20f7 100644
--- a/src/tiled/propertybrowser.cpp
+++ b/src/tiled/propertybrowser.cpp
@@ -385,6 +385,7 @@ static QStringList objectTypeNames()
 void PropertyBrowser::addMapObjectProperties()
 {
     QtProperty *groupProperty = mGroupManager->addProperty(tr("Object"));
+    createProperty(IdProperty, QVariant::Int, tr("ID"), groupProperty)->setEnabled(false);
     createProperty(NameProperty, QVariant::String, tr("Name"), groupProperty);
 
     QtVariantProperty *typeProperty =
@@ -395,7 +396,6 @@ void PropertyBrowser::addMapObjectProperties()
     createProperty(PositionProperty, QVariant::PointF, tr("Position"), groupProperty);
     createProperty(SizeProperty, QVariant::SizeF, tr("Size"), groupProperty);
     createProperty(RotationProperty, QVariant::Double, tr("Rotation"), groupProperty);
-    createProperty(IdProperty, QVariant::Int, tr("uniqueID"), groupProperty)->setEnabled(false);
 
     if (!static_cast<const MapObject*>(mObject)->cell().isEmpty()) {
         QtVariantProperty *flippingProperty =
@@ -805,13 +805,13 @@ void PropertyBrowser::updateProperties()
     }
     case Object::MapObjectType: {
         const MapObject *mapObject = static_cast<const MapObject*>(mObject);
+        mIdToProperty[IdProperty]->setValue(mapObject->id());
         mIdToProperty[NameProperty]->setValue(mapObject->name());
         mIdToProperty[TypeProperty]->setValue(mapObject->type());
         mIdToProperty[VisibleProperty]->setValue(mapObject->isVisible());
         mIdToProperty[PositionProperty]->setValue(mapObject->position());
         mIdToProperty[SizeProperty]->setValue(mapObject->size());
         mIdToProperty[RotationProperty]->setValue(mapObject->rotation());
-        mIdToProperty[IdProperty]->setValue(mapObject->uniqueID());
 
         if (QtVariantProperty *property = mIdToProperty[FlippingProperty]) {
             int flippingFlags = 0;