diff --git a/src/calibre/devices/libusb/libusb.c b/src/calibre/devices/libusb/libusb.c
index 219034cc17..bd159ec73d 100644
--- a/src/calibre/devices/libusb/libusb.c
+++ b/src/calibre/devices/libusb/libusb.c
@@ -125,44 +125,31 @@ static PyMethodDef libusb_methods[] = {
     {NULL, NULL, 0, NULL}
 };
 
-static struct PyModuleDef libusb_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "libusb",
-    /* m_doc      */ libusb_doc,
-    /* m_size     */ -1,
-    /* m_methods  */ libusb_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
-};
-CALIBRE_MODINIT_FUNC PyInit_libusb(void) {
-    PyObject *m;
-
+static int
+exec_module(PyObject *m) {
     // We deliberately use the default context. This is the context used by
     // libmtp and we want to ensure that the busnum/devnum numbers are the same
     // here and for libmtp.
-    if(libusb_init(NULL) != 0) {
-        return NULL;
-    }
+    if(libusb_init(NULL) != 0) return -1;
 
     Error = PyErr_NewException("libusb.Error", NULL, NULL);
-    if (Error == NULL) {
-        return NULL;
-    }
-
+    if (Error == NULL) return -1;
     cache = PyDict_New();
-    if (cache == NULL) {
-        return NULL;
-    }
-
-    m = PyModule_Create(&libusb_module);
-    if (m == NULL) {
-        return NULL;
-    }
+    if (cache == NULL) return -1;
 
     PyModule_AddObject(m, "Error", Error);
     PyModule_AddObject(m, "cache", cache);
-
-    return m;
+	return 0;
 }
+
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {
+    .m_base     = PyModuleDef_HEAD_INIT,
+    .m_name     = "libusb",
+    .m_doc      = libusb_doc,
+    .m_methods  = libusb_methods,
+    .m_slots    = slots,
+};
+
+CALIBRE_MODINIT_FUNC PyInit_libusb(void) { return PyModuleDef_Init(&module_def); }
diff --git a/src/calibre/devices/mtp/unix/libmtp.c b/src/calibre/devices/mtp/unix/libmtp.c
index 16bebea987..df653c67bd 100644
--- a/src/calibre/devices/mtp/unix/libmtp.c
+++ b/src/calibre/devices/mtp/unix/libmtp.c
@@ -711,34 +711,13 @@ static PyMethodDef libmtp_methods[] = {
 
     {NULL, NULL, 0, NULL}
 };
-
-
-static struct PyModuleDef libmtp_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "libmtp",
-    /* m_doc      */ libmtp_doc,
-    /* m_size     */ -1,
-    /* m_methods  */ libmtp_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
-};
-CALIBRE_MODINIT_FUNC PyInit_libmtp(void) {
+static int
+exec_module(PyObject *m) {
     DeviceType.tp_new = PyType_GenericNew;
-    if (PyType_Ready(&DeviceType) < 0) {
-        return NULL;
-    }
-
-    PyObject *m = PyModule_Create(&libmtp_module);
-    if (m == NULL) {
-        return NULL;
-    }
+    if (PyType_Ready(&DeviceType) < 0) return -1;
 
     MTPError = PyErr_NewException("libmtp.MTPError", NULL, NULL);
-    if (MTPError == NULL) {
-        return NULL;
-    }
+    if (MTPError == NULL) return -1;
     PyModule_AddObject(m, "MTPError", MTPError);
 
     // Redirect stdout to get rid of the annoying message about mtpz. Really,
@@ -769,5 +748,17 @@ CALIBRE_MODINIT_FUNC PyInit_libmtp(void) {
     PyModule_AddIntMacro(m, LIBMTP_DEBUG_DATA);
     PyModule_AddIntMacro(m, LIBMTP_DEBUG_ALL);
 
-    return m;
+	return 0;
 }
+
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {
+    .m_base     = PyModuleDef_HEAD_INIT,
+    .m_name     = "libmtp",
+    .m_doc      = libmtp_doc,
+    .m_methods  = libmtp_methods,
+    .m_slots    = slots,
+};
+
+CALIBRE_MODINIT_FUNC PyInit_libmtp(void) { return PyModuleDef_Init(&module_def); }
diff --git a/src/calibre/devices/mtp/windows/wpd.cpp b/src/calibre/devices/mtp/windows/wpd.cpp
index 77297c1c8f..44d4cd3931 100644
--- a/src/calibre/devices/mtp/windows/wpd.cpp
+++ b/src/calibre/devices/mtp/windows/wpd.cpp
@@ -183,50 +183,36 @@ static PyMethodDef wpd_methods[] = {
     {NULL, NULL, 0, NULL}
 };
 
-static struct PyModuleDef wpd_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "wpd",
-    /* m_doc      */ wpd_doc,
-    /* m_size     */ -1,
-    /* m_methods  */ wpd_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
-};
-
-CALIBRE_MODINIT_FUNC PyInit_wpd(void) {
-    PyObject *m;
-
+static int
+exec_module(PyObject *m) {
     wpd::DeviceType.tp_new = PyType_GenericNew;
-    if (PyType_Ready(&wpd::DeviceType) < 0)
-        return NULL;
-
-    m = PyModule_Create(&wpd_module);
-    if (m == NULL) {
-        return NULL;
-    }
+    if (PyType_Ready(&wpd::DeviceType) < 0) return -1;
 
     WPDError = PyErr_NewException("wpd.WPDError", NULL, NULL);
-    if (WPDError == NULL) {
-        return NULL;
-    }
+    if (WPDError == NULL) return -1;
     PyModule_AddObject(m, "WPDError", WPDError);
 
     NoWPD = PyErr_NewException("wpd.NoWPD", NULL, NULL);
-    if (NoWPD == NULL) {
-        return NULL;
-    }
+    if (NoWPD == NULL) return -1;
     PyModule_AddObject(m, "NoWPD", NoWPD);
 
     WPDFileBusy = PyErr_NewException("wpd.WPDFileBusy", NULL, NULL);
-    if (WPDFileBusy == NULL) {
-        return NULL;
-    }
+    if (WPDFileBusy == NULL) return -1;
     PyModule_AddObject(m, "WPDFileBusy", WPDFileBusy);
 
     Py_INCREF(&DeviceType);
     PyModule_AddObject(m, "Device", (PyObject *)&DeviceType);
-
-    return m;
+	return 0;
+}
+
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, (void*)exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {PyModuleDef_HEAD_INIT};
+
+CALIBRE_MODINIT_FUNC PyInit_wpd(void) {
+	module_def.m_name = "wpd";
+	module_def.m_slots = slots;
+	module_def.m_doc = wpd_doc;
+	module_def.m_methods = wpd_methods;
+	return PyModuleDef_Init(&module_def);
 }
diff --git a/src/calibre/devices/usbobserver/usbobserver.c b/src/calibre/devices/usbobserver/usbobserver.c
index 39c4d18a82..89f23c4a59 100644
--- a/src/calibre/devices/usbobserver/usbobserver.c
+++ b/src/calibre/devices/usbobserver/usbobserver.c
@@ -460,21 +460,17 @@ static PyMethodDef usbobserver_methods[] = {
 
     {NULL, NULL, 0, NULL}
 };
+static int
+exec_module(PyObject *module) { return 0; }
 
-static struct PyModuleDef usbobserver_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "usbobserver",
-    /* m_doc      */ usbobserver_doc,
-    /* m_size     */ -1,
-    /* m_methods  */ usbobserver_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {
+    .m_base     = PyModuleDef_HEAD_INIT,
+    .m_name     = "usbobserver",
+    .m_doc      = usbobserver_doc,
+    .m_methods  = usbobserver_methods,
+    .m_slots    = slots,
 };
-CALIBRE_MODINIT_FUNC PyInit_usbobserver(void) {
-    PyObject *m = NULL;
-    m = PyModule_Create(&usbobserver_module);
 
-    return m;
-}
+CALIBRE_MODINIT_FUNC PyInit_usbobserver(void) { return PyModuleDef_Init(&module_def); }
diff --git a/src/calibre/utils/cocoa_wrapper.c b/src/calibre/utils/cocoa_wrapper.c
index 612911f06c..ee95403959 100644
--- a/src/calibre/utils/cocoa_wrapper.c
+++ b/src/calibre/utils/cocoa_wrapper.c
@@ -101,22 +101,16 @@ static PyMethodDef module_methods[] = {
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 
+static int
+exec_module(PyObject *module) { return 0; }
 
-static struct PyModuleDef cocoa_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "cocoa",
-    /* m_doc      */ "",
-    /* m_size     */ -1,
-    /* m_methods  */ module_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {
+    .m_base     = PyModuleDef_HEAD_INIT,
+    .m_name     = "cocoa",
+    .m_methods  = module_methods,
+    .m_slots    = slots,
 };
-CALIBRE_MODINIT_FUNC PyInit_cocoa(void) {
-    PyObject *m = PyModule_Create(&cocoa_module);
-    if (m == NULL) {
-        return NULL;
-    }
-    return m;
-}
+
+CALIBRE_MODINIT_FUNC PyInit_cocoa(void) { return PyModuleDef_Init(&module_def); }
diff --git a/src/calibre/utils/fonts/winfonts.cpp b/src/calibre/utils/fonts/winfonts.cpp
index 3f2103b8c1..3eb0d122a8 100644
--- a/src/calibre/utils/fonts/winfonts.cpp
+++ b/src/calibre/utils/fonts/winfonts.cpp
@@ -234,27 +234,8 @@ static PyMethodDef winfonts_methods[] = {
 
     {NULL, NULL, 0, NULL}
 };
-
-
-static struct PyModuleDef winfonts_module = {
-    /* m_base     */ PyModuleDef_HEAD_INIT,
-    /* m_name     */ "winfonts",
-    /* m_doc      */ winfonts_doc,
-    /* m_size     */ -1,
-    /* m_methods  */ winfonts_methods,
-    /* m_slots    */ 0,
-    /* m_traverse */ 0,
-    /* m_clear    */ 0,
-    /* m_free     */ 0,
-};
-
-CALIBRE_MODINIT_FUNC PyInit_winfonts(void) {
-    PyObject *m;
-    m = PyModule_Create(&winfonts_module);
-    if (m == NULL) {
-        return NULL;
-    }
-
+static int
+exec_module(PyObject *m) {
     PyModule_AddIntMacro(m, FW_DONTCARE);
     PyModule_AddIntMacro(m, FW_THIN);
     PyModule_AddIntMacro(m, FW_EXTRALIGHT);
@@ -271,5 +252,17 @@ CALIBRE_MODINIT_FUNC PyInit_winfonts(void) {
     PyModule_AddIntMacro(m, FW_HEAVY);
     PyModule_AddIntMacro(m, FW_BLACK);
 
-    return m;
+	return 0;
+}
+
+static PyModuleDef_Slot slots[] = { {Py_mod_exec, (void*)exec_module}, {0, NULL} };
+
+static struct PyModuleDef module_def = {PyModuleDef_HEAD_INIT};
+
+CALIBRE_MODINIT_FUNC PyInit_winfonts(void) {
+	module_def.m_name = "winfonts";
+	module_def.m_slots = slots;
+	module_def.m_doc = winfonts_doc;
+	module_def.m_methods = winfonts_methods;
+	return PyModuleDef_Init(&module_def);
 }
diff --git a/src/calibre/utils/windows/winsapi.cpp b/src/calibre/utils/windows/winsapi.cpp
index 7c6d5d7c05..d67c974fcf 100644
--- a/src/calibre/utils/windows/winsapi.cpp
+++ b/src/calibre/utils/windows/winsapi.cpp
@@ -506,10 +506,9 @@ exec_module(PyObject *m) {
 
 static PyModuleDef_Slot slots[] = { {Py_mod_exec, (void*)exec_module}, {0, NULL} };
 
-static struct PyModuleDef module_def = {0};
+static struct PyModuleDef module_def = {PyModuleDef_HEAD_INIT};
 
 CALIBRE_MODINIT_FUNC PyInit_winsapi(void) {
-    module_def.m_base     = PyModuleDef_HEAD_INIT;
     module_def.m_name     = "winsapi";
     module_def.m_doc      = "SAPI wrapper";
     module_def.m_methods  = winsapi_methods;
diff --git a/src/calibre/utils/windows/winutil.cpp b/src/calibre/utils/windows/winutil.cpp
index c2f9a5db0b..ff81b18232 100644
--- a/src/calibre/utils/windows/winutil.cpp
+++ b/src/calibre/utils/windows/winutil.cpp
@@ -1395,10 +1395,9 @@ exec_module(PyObject *m) {
 
 static PyModuleDef_Slot slots[] = { {Py_mod_exec, (void*)exec_module}, {0, NULL} };
 
-static struct PyModuleDef module_def = {0};
+static struct PyModuleDef module_def = {PyModuleDef_HEAD_INIT};
 
 CALIBRE_MODINIT_FUNC PyInit_winutil(void) {
-    module_def.m_base     = PyModuleDef_HEAD_INIT;
     module_def.m_name     = "winutil";
     module_def.m_doc      = winutil_doc;
     module_def.m_methods  = winutil_methods;