diff --git a/src/libslic3r/SLAPrint.cpp b/src/libslic3r/SLAPrint.cpp
index 4d34c09c7b..6b691681d7 100644
--- a/src/libslic3r/SLAPrint.cpp
+++ b/src/libslic3r/SLAPrint.cpp
@@ -1182,11 +1182,18 @@ sla::DrainHoles SLAPrintObject::transformed_drainhole_points() const
     assert(m_model_object != nullptr);
     auto pts = m_model_object->sla_drain_holes;
     auto tr = trafo().cast<float>();
+    auto sc = m_model_object->instances.front()->get_scaling_factor().cast<float>();
     for (sla::DrainHole &hl : pts) {
         hl.pos = tr * hl.pos;
         hl.normal = tr * hl.normal - tr.translation();
+
+        // The normal scales as a covector (and we must also
+        // undo the damage already done).
+        hl.normal = Vec3f(hl.normal(0)/(sc(0)*sc(0)),
+                          hl.normal(1)/(sc(1)*sc(1)),
+                          hl.normal(2)/(sc(2)*sc(2)));
     }
-    
+
     return pts;
 }