diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0dcaa6fb37..866050a98d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,7 @@ project(openmc C CXX)
 # Set version numbers
 set(OPENMC_VERSION_MAJOR 0)
 set(OPENMC_VERSION_MINOR 13)
-set(OPENMC_VERSION_RELEASE 3)
+set(OPENMC_VERSION_RELEASE 4)
 set(OPENMC_VERSION ${OPENMC_VERSION_MAJOR}.${OPENMC_VERSION_MINOR}.${OPENMC_VERSION_RELEASE})
 configure_file(include/openmc/version.h.in "${CMAKE_BINARY_DIR}/include/openmc/version.h" @ONLY)
 
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 988e626cf9..8dbbfc6d44 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -71,7 +71,7 @@ copyright = '2011-2023, Massachusetts Institute of Technology, UChicago Argonne
 # The short X.Y version.
 version = "0.13"
 # The full version, including alpha/beta/rc tags.
-release = "0.13.3"
+release = "0.13.4"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/include/openmc/material.h b/include/openmc/material.h
index 8db9bb6283..deaee2469b 100644
--- a/include/openmc/material.h
+++ b/include/openmc/material.h
@@ -90,6 +90,12 @@ public:
   void set_densities(
     const vector<std::string>& name, const vector<double>& density);
 
+  //! Clone the material by deep-copying all members, except for the ID,
+  //  which will get auto-assigned to the next available ID. After creating
+  //  the new material, it is added to openmc::model::materials.
+  //! \return reference to the cloned material
+  Material & clone();
+
   //----------------------------------------------------------------------------
   // Accessors
 
diff --git a/include/openmc/version.h.in b/include/openmc/version.h.in
index a518e0d63b..e1c2b0541a 100644
--- a/include/openmc/version.h.in
+++ b/include/openmc/version.h.in
@@ -10,7 +10,7 @@ namespace openmc {
 constexpr int VERSION_MAJOR {@OPENMC_VERSION_MAJOR@};
 constexpr int VERSION_MINOR {@OPENMC_VERSION_MINOR@};
 constexpr int VERSION_RELEASE {@OPENMC_VERSION_RELEASE@};
-constexpr bool VERSION_DEV {false};
+constexpr bool VERSION_DEV {true};
 constexpr std::array<int, 3> VERSION {VERSION_MAJOR, VERSION_MINOR, VERSION_RELEASE};
 // clang-format on
 
diff --git a/openmc/__init__.py b/openmc/__init__.py
index f94cd038f8..ac9e02e168 100644
--- a/openmc/__init__.py
+++ b/openmc/__init__.py
@@ -38,4 +38,4 @@ from .config import *
 from openmc.model import rectangular_prism, hexagonal_prism, Model
 
 
-__version__ = '0.13.3'
+__version__ = '0.13.4-dev'
diff --git a/src/material.cpp b/src/material.cpp
index 74a8d7e350..82dd0d4d9e 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -353,6 +353,35 @@ Material::~Material()
   model::material_map.erase(id_);
 }
 
+Material & Material::clone()
+{
+  std::unique_ptr<Material> mat = std::make_unique<Material>();
+
+  // set all other parameters to whatever the calling Material has
+  mat->name_ = name_;
+  mat->nuclide_ = nuclide_;
+  mat->element_ = element_;
+  mat->ncrystal_mat_ = ncrystal_mat_;
+  mat->atom_density_ = atom_density_;
+  mat->density_ = density_;
+  mat->density_gpcc_ = density_gpcc_;
+  mat->volume_ = volume_;
+  mat->fissionable_ = fissionable_;
+  mat->depletable_ = depletable_;
+  mat->p0_ = p0_;
+  mat->mat_nuclide_index_ = mat_nuclide_index_;
+  mat->thermal_tables_ = thermal_tables_;
+  mat->temperature_ = temperature_;
+
+  if (ttb_)
+    mat->ttb_ = std::make_unique<Bremsstrahlung>(*ttb_);
+
+  mat->index_ = model::materials.size();
+  mat->set_id(C_NONE);
+  model::materials.push_back(std::move(mat));
+  return *model::materials.back();
+}
+
 void Material::finalize()
 {
   // Set fissionable if any nuclide is fissionable