diff --git a/source/blender/modifiers/intern/MOD_grease_pencil_thickness.cc b/source/blender/modifiers/intern/MOD_grease_pencil_thickness.cc
index ec308796217..f48a2e1614b 100644
--- a/source/blender/modifiers/intern/MOD_grease_pencil_thickness.cc
+++ b/source/blender/modifiers/intern/MOD_grease_pencil_thickness.cc
@@ -104,8 +104,8 @@ static void deform_drawing(const ModifierData &md,
   MutableSpan<float> radii = drawing.radii_for_write();
   const OffsetIndices points_by_curve = curves.points_by_curve();
   bke::MutableAttributeAccessor attributes = curves.attributes_for_write();
-  const VArray<float> vgroup_weights = *attributes.lookup_or_default<float>(
-      mmd.influence.vertex_group_name, bke::AttrDomain::Point, 1.0f);
+  const VArray<float> vgroup_weights = modifier::greasepencil::get_influence_vertex_weights(
+      curves, mmd.influence);
   const bool is_normalized = (mmd.flag & MOD_GREASE_PENCIL_THICK_NORMALIZE) != 0;
   const bool is_inverted = ((mmd.flag & MOD_GREASE_PENCIL_THICK_WEIGHT_FACTOR) == 0) &&
                            ((mmd.influence.flag & GREASE_PENCIL_INFLUENCE_INVERT_VERTEX_GROUP) !=