diff --git a/src/wrap_cl.hpp b/src/wrap_cl.hpp
index f76aba6b18054b9533945f735289b989e1240360..d1948cc8c6307fad77903d790624d4cd3625536a 100644
--- a/src/wrap_cl.hpp
+++ b/src/wrap_cl.hpp
@@ -2348,8 +2348,8 @@ namespace pyopencl
       py::object py_buffer_origin,
       py::object py_host_origin,
       py::object py_region,
-      py::sequence py_buffer_pitches,
-      py::sequence py_host_pitches,
+      py::object py_buffer_pitches,
+      py::object py_host_pitches,
       py::object py_wait_for,
       bool is_blocking
       )
diff --git a/src/wrap_cl_part_1.cpp b/src/wrap_cl_part_1.cpp
index 01a62ab30cd5e230a3c5c9e44c938b47791b5c60..a87158f95344ba3e0c1edcffbffc98966bf22c81 100644
--- a/src/wrap_cl_part_1.cpp
+++ b/src/wrap_cl_part_1.cpp
@@ -309,8 +309,8 @@ void pyopencl_expose_part_1(py::module &m)
       py::arg("buffer_origin"),
       py::arg("host_origin"),
       py::arg("region"),
-      py::arg("buffer_pitches")=py::tuple(),
-      py::arg("host_pitches")=py::tuple(),
+      py::arg("buffer_pitches")=py::none(),
+      py::arg("host_pitches")=py::none(),
       py::arg("wait_for")=py::none(),
       py::arg("is_blocking")=true
       );
@@ -321,8 +321,8 @@ void pyopencl_expose_part_1(py::module &m)
       py::arg("buffer_origin"),
       py::arg("host_origin"),
       py::arg("region"),
-      py::arg("buffer_pitches")=py::tuple(),
-      py::arg("host_pitches")=py::tuple(),
+      py::arg("buffer_pitches")=py::none(),
+      py::arg("host_pitches")=py::none(),
       py::arg("wait_for")=py::none(),
       py::arg("is_blocking")=true
       );
@@ -333,8 +333,8 @@ void pyopencl_expose_part_1(py::module &m)
       py::arg("src_origin"),
       py::arg("dst_origin"),
       py::arg("region"),
-      py::arg("src_pitches")=py::tuple(),
-      py::arg("dst_pitches")=py::tuple(),
+      py::arg("src_pitches")=py::none(),
+      py::arg("dst_pitches")=py::none(),
       py::arg("wait_for")=py::none()
       );
 #endif
diff --git a/src/wrap_helpers.hpp b/src/wrap_helpers.hpp
index 651274e021791af6db2fe6bcb78fcbdcef8c84b7..bf6853ea919509b679f799d7937c109bffbba8ad 100644
--- a/src/wrap_helpers.hpp
+++ b/src/wrap_helpers.hpp
@@ -86,7 +86,7 @@ namespace py = pybind11;
   size_t NAME[2] = {0, 0}; \
   if (py_##NAME.ptr() != Py_None) \
   { \
-    py::tuple py_tup_##NAME = py_##NAME; \
+    py::tuple py_tup_##NAME = py::cast<py::sequence>(py_##NAME);	\
     size_t my_len = len(py_tup_##NAME); \
     if (my_len > 2) \
       throw error("transfer", CL_INVALID_VALUE, #NAME "has too many components"); \