diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 30745ab806..d43f1cf528 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -671,6 +671,9 @@ sub load_model_objects {
             # add a default instance and center object around origin
             $o->center_around_origin;  # also aligns object to Z = 0
             $o->add_instance(offset => $bed_centerf);
+        } else {
+            # if object has defined positions we still need to ensure it's aligned to Z = 0
+            $o->align_to_ground;
         }
         
         {
diff --git a/xs/src/libslic3r/Model.cpp b/xs/src/libslic3r/Model.cpp
index 9182cf56b9..b1694190e3 100644
--- a/xs/src/libslic3r/Model.cpp
+++ b/xs/src/libslic3r/Model.cpp
@@ -597,6 +597,20 @@ ModelObject::instance_bounding_box(size_t instance_idx) const
     return bb;
 }
 
+void
+ModelObject::align_to_ground()
+{
+    // calculate the displacements needed to 
+    // center this object around the origin
+	BoundingBoxf3 bb;
+	for (const ModelVolume* v : this->volumes)
+		if (!v->modifier)
+			bb.merge(v->mesh.bounding_box());
+    
+    this->translate(0, 0, -bb.min.z);
+    this->origin_translation.translate(0, 0, -bb.min.z);
+}
+
 void
 ModelObject::center_around_origin()
 {
diff --git a/xs/src/libslic3r/Model.hpp b/xs/src/libslic3r/Model.hpp
index 9c8e0d1e20..1b6c6d6c20 100644
--- a/xs/src/libslic3r/Model.hpp
+++ b/xs/src/libslic3r/Model.hpp
@@ -149,6 +149,7 @@ class ModelObject
     TriangleMesh raw_mesh() const;
     BoundingBoxf3 raw_bounding_box() const;
     BoundingBoxf3 instance_bounding_box(size_t instance_idx) const;
+    void align_to_ground();
     void center_around_origin();
     void translate(const Vectorf3 &vector);
     void translate(coordf_t x, coordf_t y, coordf_t z);
diff --git a/xs/xsp/Model.xsp b/xs/xsp/Model.xsp
index c5c7006068..53f6cc8f3c 100644
--- a/xs/xsp/Model.xsp
+++ b/xs/xsp/Model.xsp
@@ -207,6 +207,7 @@ ModelMaterial::attributes()
     bool needed_repair() const;
     int materials_count() const;
     int facets_count();
+    void align_to_ground();
     void center_around_origin();
     void translate(double x, double y, double z);
     void scale_xyz(Pointf3* versor)