diff --git a/include/carma.hpp b/include/carma.hpp
index 162f51e..5c66d6f 100644
--- a/include/carma.hpp
+++ b/include/carma.hpp
@@ -1,10 +1,9 @@
 /*  carma/carma: Bidirectional coverter of Numpy arrays and Armadillo objects
- *  Copyright (c) 2022 Ralph Urlus <rurlus.dev@gmail.com>
+ *  Copyright (c) 2023 Ralph Urlus <rurlus.dev@gmail.com>
  *  All rights reserved. Use of this source code is governed by a
  *  Apache-2.0 license that can be found in the LICENSE file.
  */
-#ifndef INCLUDE_CARMA_
-#define INCLUDE_CARMA_
+#pragma once
 
 /* If the Numpy allocator/deallocator have not been set through
  * the carma_armadillo target ARMA_ALIEN_MEM_ALLOC_FUNCTION and
@@ -97,5 +96,3 @@ static carma_config_debug_message carma_config_debug_message_print;
 #endif  // CARMA_EXTRA_DEBUG
 
 }  // namespace carma
-
-#endif  // INCLUDE_CARMA_
diff --git a/include/carma_bits/array_view.hpp b/include/carma_bits/array_view.hpp
index 7123101..b466334 100644
--- a/include/carma_bits/array_view.hpp
+++ b/include/carma_bits/array_view.hpp
@@ -1,5 +1,4 @@
-#ifndef INCLUDE_CARMA_BITS_ARRAY_VIEW_HPP_
-#define INCLUDE_CARMA_BITS_ARRAY_VIEW_HPP_
+#pragma once
 
 // pybind11 include required even if not explicitly used
 // to prevent link with pythonXX_d.lib on Win32
@@ -193,4 +192,3 @@ class ArrayView {
 
 }  // namespace internal
 }  // namespace carma
-#endif  // INCLUDE_CARMA_BITS_ARRAY_VIEW_HPP_
diff --git a/include/carma_bits/converters.hpp b/include/carma_bits/converters.hpp
index 3f97d4e..b7155ce 100644
--- a/include/carma_bits/converters.hpp
+++ b/include/carma_bits/converters.hpp
@@ -1,5 +1,4 @@
-#ifndef INCLUDE_CARMA_BITS_CONVERTERS_HPP_
-#define INCLUDE_CARMA_BITS_CONVERTERS_HPP_
+#pragma once
 
 #include <armadillo>
 #include <carma_bits/array_view.hpp>
@@ -335,4 +334,3 @@ auto arr_to_cube(numpyT arr) {
 }
 
 }  // namespace carma
-#endif  // INCLUDE_CARMA_BITS_CONVERTERS_HPP_
diff --git a/include/carma_bits/numpy_alloc.hpp b/include/carma_bits/numpy_alloc.hpp
index 60ba4f5..adb1c9c 100644
--- a/include/carma_bits/numpy_alloc.hpp
+++ b/include/carma_bits/numpy_alloc.hpp
@@ -3,8 +3,7 @@
  *  All rights reserved. Use of this source code is governed by a
  *  Apache-2.0 license that can be found in the LICENSE file.
  */
-#ifndef INCLUDE_CARMA_BITS_NUMPY_ALLOC_HPP_
-#define INCLUDE_CARMA_BITS_NUMPY_ALLOC_HPP_
+#pragma once
 
 // pybind11 include required even if not explicitly used
 // to prevent link with pythonXX_d.lib on Win32
@@ -36,7 +35,7 @@ inline void npy_free(void* ptr) {
     const auto& api = internal::npy_api::get();
 #ifdef CARMA_EXTRA_DEBUG
     std::cout << "|carma| freeing " << ptr << "\n";
-#endif  // ARMA_EXTRA_DEBUG
+#endif  // CARMA_EXTRA_DEBUG
     api.PyDataMem_FREE_(ptr);
 }  // npy_free
 
@@ -51,4 +50,3 @@ inline void npy_free(void* ptr) {
 #ifndef CARMA_ARMA_ALIEN_MEM_FUNCTIONS_SET
 #define CARMA_ARMA_ALIEN_MEM_FUNCTIONS_SET true
 #endif
-#endif  // INCLUDE_CARMA_BITS_NUMPY_ALLOC_HPP_
diff --git a/include/carma_bits/numpy_api.hpp b/include/carma_bits/numpy_api.hpp
index da9a0b4..cce0702 100644
--- a/include/carma_bits/numpy_api.hpp
+++ b/include/carma_bits/numpy_api.hpp
@@ -1,5 +1,4 @@
-#ifndef INCLUDE_CARMA_BITS_NUMPY_API_HPP_
-#define INCLUDE_CARMA_BITS_NUMPY_API_HPP_
+#pragma once
 
 #include <Python.h>
 #include <pybind11/numpy.h>
@@ -39,8 +38,16 @@ struct npy_api {
     int (*PyArray_Size_)(PyObject *src);
     int (*PyArray_CopyInto_)(PyArrayObject *dest, PyArrayObject *src);
     PyObject *(*PyArray_NewCopy_)(PyArrayObject *, int);
-    PyObject *(*PyArray_NewFromDescr_)(PyTypeObject *subtype, PyArray_Descr *descr, int nd, npy_intp const *dims,
-                                       npy_intp const *strides, void *data, int flags, PyObject *obj);
+    PyObject *(*PyArray_NewFromDescr_)(
+        PyTypeObject *subtype,
+        PyArray_Descr *descr,
+        int nd,
+        npy_intp const *dims,
+        npy_intp const *strides,
+        void *data,
+        int flags,
+        PyObject *obj
+    );
     void (*PyArray_Free_)(PyArrayObject *, void *ptr);
     PyObject *(*PyArray_NewLikeArray_)(PyArrayObject *prototype, NPY_ORDER order, PyArray_Descr *descr, int subok);
     void *(*PyDataMem_NEW_)(size_t nbytes);
@@ -81,4 +88,3 @@ struct npy_api {
 
 }  // namespace internal
 }  // namespace carma
-#endif  // INCLUDE_CARMA_BITS_NUMPY_API_HPP_
diff --git a/include/carma_bits/to_arma.hpp b/include/carma_bits/to_arma.hpp
index 57e248f..f80e5b7 100644
--- a/include/carma_bits/to_arma.hpp
+++ b/include/carma_bits/to_arma.hpp
@@ -1,5 +1,4 @@
-#ifndef INCLUDE_CARMA_BITS_TO_ARMA_HPP_
-#define INCLUDE_CARMA_BITS_TO_ARMA_HPP_
+#pragma once
 
 #include <armadillo>
 #include <carma_bits/array_view.hpp>
@@ -836,4 +835,3 @@ struct toArma {
 }  // namespace internal
 
 }  // namespace carma
-#endif  // INCLUDE_CARMA_BITS_TO_ARMA_HPP_
diff --git a/include/carma_bits/to_numpy.hpp b/include/carma_bits/to_numpy.hpp
index 435aa01..e19ea52 100644
--- a/include/carma_bits/to_numpy.hpp
+++ b/include/carma_bits/to_numpy.hpp
@@ -1,5 +1,4 @@
-#ifndef INCLUDE_CARMA_BITS_TO_NUMPY_HPP_
-#define INCLUDE_CARMA_BITS_TO_NUMPY_HPP_
+#pragma once
 
 #include <armadillo>
 #include <carma_bits/common.hpp>
@@ -10,6 +9,17 @@ namespace carma {
 
 namespace internal {
 
+// https://github.com/pybind/pybind11/issues/1042#issuecomment-642215028
+// template <typename armaT>
+// inline py::array_t<typename armaT::value_type> as_pyarray(armaT &&seq) {
+//     auto size = seq.size();
+//     auto data = seq.data();
+//     std::unique_ptr<armaT> seq_ptr = std::make_unique<armaT>(std::move(seq));
+//     auto capsule = py::capsule(seq_ptr.get(), [](void *p) { std::unique_ptr<armaT>(reinterpret_cast<armaT*>(p)); });
+//     seq_ptr.release();
+//     return py::array(size, data, capsule);
+// }
+
 template <typename armaT>
 inline py::capsule create_capsule(armaT data) {
     return py::capsule(data, [](void* f) {
@@ -89,4 +99,3 @@ py::array_t<eT> create_reference_array(const ArmaView& src);
 
 }  // namespace internal
 }  // namespace carma
-#endif  // INCLUDE_CARMA_BITS_TO_NUMPY_HPP_