diff --git a/src/GUI/Plater/PlaterObject.hpp b/src/GUI/Plater/PlaterObject.hpp
index 3d06601c3..d1d2f7056 100644
--- a/src/GUI/Plater/PlaterObject.hpp
+++ b/src/GUI/Plater/PlaterObject.hpp
@@ -13,7 +13,7 @@ namespace Slic3r { namespace GUI {
 class PlaterObject {
 public:
     std::string name {""};
-    size_t identifier {0U};
+    int identifier {0};
     std::string input_file {""};
     int input_file_obj_idx {-1};