diff --git a/source/blender/blenkernel/intern/grease_pencil.cc b/source/blender/blenkernel/intern/grease_pencil.cc
index 44afcfc9eb2..5d048a6bf5d 100644
--- a/source/blender/blenkernel/intern/grease_pencil.cc
+++ b/source/blender/blenkernel/intern/grease_pencil.cc
@@ -3243,7 +3243,7 @@ blender::bke::greasepencil::Layer &GreasePencil::add_layer(const blender::String
   using namespace blender;
   std::string unique_name = check_name_is_unique ? unique_layer_name(*this, name) : name.c_str();
   const int numLayers = layers().size();
-  CustomData_realloc(&layers_data, numLayers, numLayers + 1);
+  CustomData_realloc(&layers_data, numLayers, numLayers + 1, CD_SET_DEFAULT);
   bke::greasepencil::Layer *new_layer = MEM_new<bke::greasepencil::Layer>(__func__, unique_name);
   /* Hide masks by default. */
   new_layer->base.flag |= GP_LAYER_TREE_NODE_HIDE_MASKS;
@@ -3288,8 +3288,15 @@ blender::bke::greasepencil::Layer &GreasePencil::duplicate_layer(
 {
   using namespace blender;
   std::string unique_name = unique_layer_name(*this, duplicate_layer.name());
+  std::optional<int> duplicate_layer_idx = get_layer_index(duplicate_layer);
   const int numLayers = layers().size();
   CustomData_realloc(&layers_data, numLayers, numLayers + 1);
+  if (duplicate_layer_idx.has_value()) {
+    for (const int layer_index : IndexRange(layers_data.totlayer)) {
+      CustomData_copy_data_layer(
+          &layers_data, &layers_data, layer_index, layer_index, *duplicate_layer_idx, numLayers, 1);
+    }
+  }
   bke::greasepencil::Layer *new_layer = MEM_new<bke::greasepencil::Layer>(__func__,
                                                                           duplicate_layer);
   root_group().add_node(new_layer->as_node());