1 files changed, 11 insertions, 0 deletions
diff --git a/source/blender/blenkernel/intern/geometry_set_instances.cc b/source/blender/blenkernel/intern/geometry_set_instances.cc
index 97892075eca..81984321b70 100644
--- a/source/blender/blenkernel/intern/geometry_set_instances.cc
+++ b/source/blender/blenkernel/intern/geometry_set_instances.cc
@@ -563,6 +563,17 @@ static void join_curve_splines(Span<GeometryInstanceGroup> set_groups, CurveComp
     }
   }
 
+  for (SplinePtr &spline : new_curve->splines()) {
+    /* Spline instances should have no custom attributes, since they always come
+     * from original objects which currenty do not support custom attributes.
+     *
+     * This is only true as long as a GeometrySet cannot be instanced directly. */
+    BLI_assert(spline->attributes.data.totlayer == 0);
+    UNUSED_VARS_NDEBUG(spline);
+  }
+
+  new_curve->attributes.reallocate(new_curve->splines().size());
+
   result.replace(new_curve);
 }