diff --git a/src/calibre/devices/mtp/windows/device_enumeration.cpp b/src/calibre/devices/mtp/windows/device_enumeration.cpp
index c206c87333..7d9729eb36 100644
--- a/src/calibre/devices/mtp/windows/device_enumeration.cpp
+++ b/src/calibre/devices/mtp/windows/device_enumeration.cpp
@@ -22,7 +22,7 @@ IPortableDeviceValues *get_client_information() { // {{{
     if (FAILED(hr)) { hresult_set_exc("Failed to create IPortableDeviceValues", hr); return NULL; }
 
     Py_BEGIN_ALLOW_THREADS;
-    hr = client_information->SetStringValue(WPD_CLIENT_NAME, client_info.name);
+    hr = client_information->SetStringValue(WPD_CLIENT_NAME, client_info.name.ptr());
     Py_END_ALLOW_THREADS;
     if (FAILED(hr)) { hresult_set_exc("Failed to set client name", hr); return NULL; }
     Py_BEGIN_ALLOW_THREADS;
diff --git a/src/calibre/devices/mtp/windows/global.h b/src/calibre/devices/mtp/windows/global.h
index 2a9361c18b..50552a7a0d 100644
--- a/src/calibre/devices/mtp/windows/global.h
+++ b/src/calibre/devices/mtp/windows/global.h
@@ -13,6 +13,7 @@
 #include <Objbase.h>
 #include <PortableDeviceApi.h>
 #include <PortableDevice.h>
+#include "../../../utils/windows/common.h"
 
 #define ENSURE_WPD(retval) \
     if (portable_device_manager == NULL) { PyErr_SetString(NoWPD, "No WPD service available."); return retval; }
@@ -27,7 +28,7 @@ extern IPortableDeviceManager *portable_device_manager;
 
 // Application info
 typedef struct {
-    wchar_t *name;
+    wchar_raii name;
     unsigned int major_version;
     unsigned int minor_version;
     unsigned int revision;
@@ -63,4 +64,3 @@ extern PyObject* delete_object(IPortableDevice *device, const wchar_t *object_id
 extern PyObject* put_file(IPortableDevice *device, const wchar_t *parent_id, const wchar_t *name, PyObject *src, unsigned PY_LONG_LONG size, PyObject *callback);
 
 }
-
diff --git a/src/calibre/devices/mtp/windows/utils.cpp b/src/calibre/devices/mtp/windows/utils.cpp
index 363425aca5..4d7976e116 100644
--- a/src/calibre/devices/mtp/windows/utils.cpp
+++ b/src/calibre/devices/mtp/windows/utils.cpp
@@ -6,7 +6,6 @@
  */
 
 #include "global.h"
-#include "../../../utils/windows/common.h"
 
 using namespace wpd;
 
diff --git a/src/calibre/devices/mtp/windows/wpd.cpp b/src/calibre/devices/mtp/windows/wpd.cpp
index c1ddf18c51..0cbca6ce8a 100644
--- a/src/calibre/devices/mtp/windows/wpd.cpp
+++ b/src/calibre/devices/mtp/windows/wpd.cpp
@@ -18,7 +18,7 @@ IPortableDeviceManager *wpd::portable_device_manager = NULL;
 // Flag indicating if COM has been initialized
 static int _com_initialized = 0;
 // Application Info
-wpd::ClientInfo wpd::client_info = {NULL, 0, 0, 0};
+wpd::ClientInfo wpd::client_info = {0};
 
 extern IPortableDeviceValues* wpd::get_client_information();
 extern IPortableDevice* wpd::open_device(const wchar_t *pnp_id, IPortableDeviceValues *client_information);
@@ -28,10 +28,7 @@ extern PyObject* wpd::get_device_information(IPortableDevice *device, IPortableD
 static PyObject *
 wpd_init(PyObject *self, PyObject *args) {
     HRESULT hr;
-    PyObject *o;
-    if (!PyArg_ParseTuple(args, "OIII", &o, &client_info.major_version, &client_info.minor_version, &client_info.revision)) return NULL;
-    client_info.name = unicode_to_wchar(o);
-    if (client_info.name == NULL) return NULL;
+    if (!PyArg_ParseTuple(args, "O&III", py_to_wchar_no_none, &client_info.name, &client_info.major_version, &client_info.minor_version, &client_info.revision)) return NULL;
 
     if (!_com_initialized) {
         Py_BEGIN_ALLOW_THREADS;
@@ -75,7 +72,7 @@ wpd_uninit(PyObject *self, PyObject *args) {
         _com_initialized = 0;
     }
 
-    if (client_info.name != NULL) { free(client_info.name); }
+    client_info.name.release();
     // hresult_set_exc("test", HRESULT_FROM_WIN32(ERROR_ACCESS_DENIED)); return NULL;
 
     Py_RETURN_NONE;
@@ -137,27 +134,24 @@ wpd_enumerate_devices(PyObject *self, PyObject *args) {
 // device_info() {{{
 static PyObject *
 wpd_device_info(PyObject *self, PyObject *args) {
-    PyObject *py_pnp_id, *ans = NULL;
-    wchar_t *pnp_id;
+    PyObject *ans = NULL;
     IPortableDeviceValues *client_information = NULL;
     IPortableDevice *device = NULL;
 
     ENSURE_WPD(NULL);
 
-    if (!PyArg_ParseTuple(args, "O", &py_pnp_id)) return NULL;
-    pnp_id = unicode_to_wchar(py_pnp_id);
-    if (pnp_id == NULL) return NULL;
-    if (wcslen(pnp_id) < 1) { PyErr_SetString(WPDError, "The PNP id must not be empty."); return NULL; }
+    wchar_raii pnp_id;
+    if (!PyArg_ParseTuple(args, "O&", py_to_wchar_no_none, &pnp_id)) return NULL;
+    if (wcslen(pnp_id.ptr()) < 1) { PyErr_SetString(WPDError, "The PNP id must not be empty."); return NULL; }
 
     client_information = get_client_information();
     if (client_information != NULL) {
-        device = open_device(pnp_id, client_information);
+        device = open_device(pnp_id.ptr(), client_information);
         if (device != NULL) {
             ans = get_device_information(device, NULL);
         }
     }
 
-    if (pnp_id != NULL) free(pnp_id);
     if (client_information != NULL) client_information->Release();
     if (device != NULL) {device->Close(); device->Release();}
     return ans;
diff --git a/src/calibre/utils/windows/common.h b/src/calibre/utils/windows/common.h
index dd45f1a797..a3a845a73f 100644
--- a/src/calibre/utils/windows/common.h
+++ b/src/calibre/utils/windows/common.h
@@ -36,7 +36,8 @@ class wchar_raii {
 		wchar_raii() : handle(NULL) {}
 		wchar_raii(wchar_t *h) : handle(h) {}
 
-		~wchar_raii() {
+		~wchar_raii() { release(); }
+		void release() {
 			if (handle) {
 				PyMem_Free(handle);
 				handle = NULL;