diff --git a/Doc/c-api/init.rst b/Doc/c-api/init.rst
index 7d9eefb..56cf77a 100644
--- a/Doc/c-api/init.rst
+++ b/Doc/c-api/init.rst
@@ -830,7 +830,7 @@
    the caller should assume no current thread state is available.
 
 
-.. c:function:: int PyThreadState_SetAsyncExc(long id, PyObject *exc)
+.. c:function:: int PyThreadState_SetAsyncExc(unsigned long id, PyObject *exc)
 
    Asynchronously raise an exception in a thread. The *id* argument is the thread
    id of the target thread; *exc* is the exception object to be raised. This
@@ -840,6 +840,9 @@
    zero if the thread id isn't found.  If *exc* is :const:`NULL`, the pending
    exception (if any) for the thread is cleared. This raises no exceptions.
 
+   .. versionchanged:: 3.7
+      The type of the *id* parameter changed from :c:type:`long` to
+      :c:type:`unsigned long`.
 
 .. c:function:: void PyEval_AcquireThread(PyThreadState *tstate)
 
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index 4f84e6d..882d6a2 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -185,6 +185,16 @@
   (Contributed by Serhiy Storchaka in :issue:`28692`.)
 
 
+Changes in the C API
+--------------------
+
+- The type of results of :c:func:`PyThread_start_new_thread` and
+  :c:func:`PyThread_get_thread_ident`, and the *id* parameter of
+  :c:func:`PyThreadState_SetAsyncExc` changed from :c:type:`long` to
+  :c:type:`unsigned long`.
+  (Contributed by Serhiy Storchaka in :issue:`6532`.)
+
+
 Removed
 =======
 
diff --git a/Include/pystate.h b/Include/pystate.h
index afc3c0c..62254fa 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -108,7 +108,7 @@
     int gilstate_counter;
 
     PyObject *async_exc; /* Asynchronous exception to raise */
-    long thread_id; /* Thread id where this tstate was created */
+    unsigned long thread_id; /* Thread id where this tstate was created */
 
     int trash_delete_nesting;
     PyObject *trash_delete_later;
@@ -200,7 +200,7 @@
 
 PyAPI_FUNC(PyThreadState *) PyThreadState_Swap(PyThreadState *);
 PyAPI_FUNC(PyObject *) PyThreadState_GetDict(void);
-PyAPI_FUNC(int) PyThreadState_SetAsyncExc(long, PyObject *);
+PyAPI_FUNC(int) PyThreadState_SetAsyncExc(unsigned long, PyObject *);
 
 
 /* Variable and macro for in-line access to current thread state */
diff --git a/Include/pythread.h b/Include/pythread.h
index 88c4873..dbacb8b 100644
--- a/Include/pythread.h
+++ b/Include/pythread.h
@@ -17,10 +17,14 @@
     PY_LOCK_INTR
 } PyLockStatus;
 
+#ifndef Py_LIMITED_API
+#define PYTHREAD_INVALID_THREAD_ID ((unsigned long)-1)
+#endif
+
 PyAPI_FUNC(void) PyThread_init_thread(void);
-PyAPI_FUNC(long) PyThread_start_new_thread(void (*)(void *), void *);
+PyAPI_FUNC(unsigned long) PyThread_start_new_thread(void (*)(void *), void *);
 PyAPI_FUNC(void) PyThread_exit_thread(void);
-PyAPI_FUNC(long) PyThread_get_thread_ident(void);
+PyAPI_FUNC(unsigned long) PyThread_get_thread_ident(void);
 
 PyAPI_FUNC(PyThread_type_lock) PyThread_allocate_lock(void);
 PyAPI_FUNC(void) PyThread_free_lock(PyThread_type_lock);
diff --git a/Lib/_dummy_thread.py b/Lib/_dummy_thread.py
index 36e5f38..a2cae54 100644
--- a/Lib/_dummy_thread.py
+++ b/Lib/_dummy_thread.py
@@ -69,7 +69,7 @@
     available, it is safe to assume that the current process is the
     only thread.  Thus a constant can be safely returned.
     """
-    return -1
+    return 1
 
 def allocate_lock():
     """Dummy implementation of _thread.allocate_lock()."""
diff --git a/Lib/test/test_dummy_thread.py b/Lib/test/test_dummy_thread.py
index bb4bfe7..0840be6 100644
--- a/Lib/test/test_dummy_thread.py
+++ b/Lib/test/test_dummy_thread.py
@@ -111,8 +111,7 @@
     def test_ident(self):
         self.assertIsInstance(_thread.get_ident(), int,
                               "_thread.get_ident() returned a non-integer")
-        self.assertNotEqual(_thread.get_ident(), 0,
-                        "_thread.get_ident() returned 0")
+        self.assertGreater(_thread.get_ident(), 0)
 
     def test_LockType(self):
         self.assertIsInstance(_thread.allocate_lock(), _thread.LockType,
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index e6d8e50..9aeb28a 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -393,6 +393,9 @@
         thread_id = thread_info[0]
 
         d = sys._current_frames()
+        for tid in d:
+            self.assertIsInstance(tid, int)
+            self.assertGreater(tid, 0)
 
         main_id = threading.get_ident()
         self.assertIn(main_id, d)
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 6b6c4d2..5f7c0a8 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -181,6 +181,7 @@
         ctypes = import_module("ctypes")
 
         set_async_exc = ctypes.pythonapi.PyThreadState_SetAsyncExc
+        set_async_exc.argtypes = (ctypes.c_ulong, ctypes.py_object)
 
         class AsyncExc(Exception):
             pass
@@ -189,9 +190,11 @@
 
         # First check it works when setting the exception from the same thread.
         tid = threading.get_ident()
+        self.assertIsInstance(tid, int)
+        self.assertGreater(tid, 0)
 
         try:
-            result = set_async_exc(ctypes.c_long(tid), exception)
+            result = set_async_exc(tid, exception)
             # The exception is async, so we might have to keep the VM busy until
             # it notices.
             while True:
@@ -237,7 +240,7 @@
         # Try a thread id that doesn't make sense.
         if verbose:
             print("    trying nonsensical thread id")
-        result = set_async_exc(ctypes.c_long(-1), exception)
+        result = set_async_exc(-1, exception)
         self.assertEqual(result, 0)  # no thread states modified
 
         # Now raise an exception in the worker thread.
@@ -250,7 +253,7 @@
         self.assertFalse(t.finished)
         if verbose:
             print("    attempting to raise asynch exception in worker")
-        result = set_async_exc(ctypes.c_long(t.id), exception)
+        result = set_async_exc(t.id, exception)
         self.assertEqual(result, 1) # one thread state modified
         if verbose:
             print("    waiting for worker to say it caught the exception")
diff --git a/Lib/threading.py b/Lib/threading.py
index 95978d3..929a4b0 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -993,14 +993,14 @@
         #
         # Must take care to not raise an exception if _dummy_thread is being
         # used (and thus this module is being used as an instance of
-        # dummy_threading).  _dummy_thread.get_ident() always returns -1 since
+        # dummy_threading).  _dummy_thread.get_ident() always returns 1 since
         # there is only one thread if _dummy_thread is being used.  Thus
         # len(_active) is always <= 1 here, and any Thread instance created
         # overwrites the (if any) thread currently registered in _active.
         #
         # An instance of _MainThread is always created by 'threading'.  This
         # gets overwritten the instant an instance of Thread is created; both
-        # threads return -1 from _dummy_thread.get_ident() and thus have the
+        # threads return 1 from _dummy_thread.get_ident() and thus have the
         # same key in the dict.  So when the _MainThread instance created by
         # 'threading' tries to clean itself up when atexit calls this method
         # it gets a KeyError if another Thread instance was created.
diff --git a/Misc/NEWS b/Misc/NEWS
index aac10a6..97c45d4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -813,6 +813,10 @@
 C API
 -----
 
+- bpo-6532: The type of results of PyThread_start_new_thread() and
+  PyThread_get_thread_ident(), and the id parameter of
+  PyThreadState_SetAsyncExc() changed from "long" to "unsigned long".
+
 - Issue #27867: Function PySlice_GetIndicesEx() is deprecated and replaced with
   a macro if Py_LIMITED_API is not set or set to the value between 0x03050400
   and 0x03060000 (not including) or 0x03060100 or higher.  Added functions
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 4f6dddb..b30d229 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -239,7 +239,7 @@
 
 #ifdef WITH_THREAD
     PyThread_type_lock lock;
-    volatile long owner;
+    volatile unsigned long owner;
 #endif
 
     Py_ssize_t buffer_size;
diff --git a/Modules/_multiprocessing/semaphore.c b/Modules/_multiprocessing/semaphore.c
index cea962a..9614329 100644
--- a/Modules/_multiprocessing/semaphore.c
+++ b/Modules/_multiprocessing/semaphore.c
@@ -14,7 +14,7 @@
 typedef struct {
     PyObject_HEAD
     SEM_HANDLE handle;
-    long last_tid;
+    unsigned long last_tid;
     int count;
     int maxvalue;
     int kind;
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index 7743999..72156b9 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -1125,7 +1125,7 @@
         if (PyThread_get_thread_ident() != self->thread_ident) {
             PyErr_Format(pysqlite_ProgrammingError,
                         "SQLite objects created in a thread can only be used in that same thread."
-                        "The object was created in thread id %ld and this is thread id %ld",
+                        "The object was created in thread id %lu and this is thread id %lu",
                         self->thread_ident, PyThread_get_thread_ident());
             return 0;
         }
diff --git a/Modules/_sqlite/connection.h b/Modules/_sqlite/connection.h
index 2860a0c..5fb410a 100644
--- a/Modules/_sqlite/connection.h
+++ b/Modules/_sqlite/connection.h
@@ -61,7 +61,7 @@
     int initialized;
 
     /* thread identification of the thread the connection was created in */
-    long thread_ident;
+    unsigned long thread_ident;
 
     pysqlite_Cache* statement_cache;
 
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 421e0b6..327fb37 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -5032,8 +5032,7 @@
 static void
 _ssl_threadid_callback(CRYPTO_THREADID *id)
 {
-    CRYPTO_THREADID_set_numeric(id,
-                                (unsigned long)PyThread_get_thread_ident());
+    CRYPTO_THREADID_set_numeric(id, PyThread_get_thread_ident());
 }
 #else
 /* deprecated CRYPTO_set_id_callback() API. */
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index bf25a19..da750c0 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -267,7 +267,7 @@
 typedef struct {
     PyObject_HEAD
     PyThread_type_lock rlock_lock;
-    long rlock_owner;
+    unsigned long rlock_owner;
     unsigned long rlock_count;
     PyObject *in_weakreflist;
 } rlockobject;
@@ -293,7 +293,7 @@
 rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds)
 {
     _PyTime_t timeout;
-    long tid;
+    unsigned long tid;
     PyLockStatus r = PY_LOCK_ACQUIRED;
 
     if (lock_acquire_parse_args(args, kwds, &timeout) < 0)
@@ -342,7 +342,7 @@
 static PyObject *
 rlock_release(rlockobject *self)
 {
-    long tid = PyThread_get_thread_ident();
+    unsigned long tid = PyThread_get_thread_ident();
 
     if (self->rlock_count == 0 || self->rlock_owner != tid) {
         PyErr_SetString(PyExc_RuntimeError,
@@ -371,11 +371,11 @@
 static PyObject *
 rlock_acquire_restore(rlockobject *self, PyObject *args)
 {
-    long owner;
+    unsigned long owner;
     unsigned long count;
     int r = 1;
 
-    if (!PyArg_ParseTuple(args, "(kl):_acquire_restore", &count, &owner))
+    if (!PyArg_ParseTuple(args, "(kk):_acquire_restore", &count, &owner))
         return NULL;
 
     if (!PyThread_acquire_lock(self->rlock_lock, 0)) {
@@ -401,7 +401,7 @@
 static PyObject *
 rlock_release_save(rlockobject *self)
 {
-    long owner;
+    unsigned long owner;
     unsigned long count;
 
     if (self->rlock_count == 0) {
@@ -415,7 +415,7 @@
     self->rlock_count = 0;
     self->rlock_owner = 0;
     PyThread_release_lock(self->rlock_lock);
-    return Py_BuildValue("kl", count, owner);
+    return Py_BuildValue("kk", count, owner);
 }
 
 PyDoc_STRVAR(rlock_release_save_doc,
@@ -427,7 +427,7 @@
 static PyObject *
 rlock_is_owned(rlockobject *self)
 {
-    long tid = PyThread_get_thread_ident();
+    unsigned long tid = PyThread_get_thread_ident();
 
     if (self->rlock_count > 0 && self->rlock_owner == tid) {
         Py_RETURN_TRUE;
@@ -1031,7 +1031,7 @@
 {
     PyObject *func, *args, *keyw = NULL;
     struct bootstate *boot;
-    long ident;
+    unsigned long ident;
 
     if (!PyArg_UnpackTuple(fargs, "start_new_thread", 2, 3,
                            &func, &args, &keyw))
@@ -1068,7 +1068,7 @@
     Py_XINCREF(keyw);
     PyEval_InitThreads(); /* Start the interpreter's thread-awareness */
     ident = PyThread_start_new_thread(t_bootstrap, (void*) boot);
-    if (ident == -1) {
+    if (ident == PYTHREAD_INVALID_THREAD_ID) {
         PyErr_SetString(ThreadError, "can't start new thread");
         Py_DECREF(func);
         Py_DECREF(args);
@@ -1077,7 +1077,7 @@
         PyMem_DEL(boot);
         return NULL;
     }
-    return PyLong_FromLong(ident);
+    return PyLong_FromUnsignedLong(ident);
 }
 
 PyDoc_STRVAR(start_new_doc,
@@ -1137,13 +1137,12 @@
 static PyObject *
 thread_get_ident(PyObject *self)
 {
-    long ident;
-    ident = PyThread_get_thread_ident();
-    if (ident == -1) {
+    unsigned long ident = PyThread_get_thread_ident();
+    if (ident == PYTHREAD_INVALID_THREAD_ID) {
         PyErr_SetString(ThreadError, "no current thread ident");
         return NULL;
     }
-    return PyLong_FromLong(ident);
+    return PyLong_FromUnsignedLong(ident);
 }
 
 PyDoc_STRVAR(get_ident_doc,
diff --git a/Modules/clinic/signalmodule.c.h b/Modules/clinic/signalmodule.c.h
index 9e16f32..2a4e935 100644
--- a/Modules/clinic/signalmodule.c.h
+++ b/Modules/clinic/signalmodule.c.h
@@ -395,16 +395,17 @@
     {"pthread_kill", (PyCFunction)signal_pthread_kill, METH_FASTCALL, signal_pthread_kill__doc__},
 
 static PyObject *
-signal_pthread_kill_impl(PyObject *module, long thread_id, int signalnum);
+signal_pthread_kill_impl(PyObject *module, unsigned long thread_id,
+                         int signalnum);
 
 static PyObject *
 signal_pthread_kill(PyObject *module, PyObject **args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
-    long thread_id;
+    unsigned long thread_id;
     int signalnum;
 
-    if (!_PyArg_ParseStack(args, nargs, "li:pthread_kill",
+    if (!_PyArg_ParseStack(args, nargs, "ki:pthread_kill",
         &thread_id, &signalnum)) {
         goto exit;
     }
@@ -463,4 +464,4 @@
 #ifndef SIGNAL_PTHREAD_KILL_METHODDEF
     #define SIGNAL_PTHREAD_KILL_METHODDEF
 #endif /* !defined(SIGNAL_PTHREAD_KILL_METHODDEF) */
-/*[clinic end generated code: output=fab3dba32c058588 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c1a3f374b2c77e5d input=a9049054013a1b77]*/
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 4fc8ebd..4a03eaf 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -678,7 +678,7 @@
     /* Arm these locks to serve as events when released */
     PyThread_acquire_lock(thread.running, 1);
 
-    if (PyThread_start_new_thread(faulthandler_thread, NULL) == -1) {
+    if (PyThread_start_new_thread(faulthandler_thread, NULL) == PYTHREAD_INVALID_THREAD_ID) {
         PyThread_release_lock(thread.running);
         Py_CLEAR(thread.file);
         PyMem_Free(header);
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index bc36d41..ed03683 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -88,7 +88,7 @@
 #ifdef WITH_THREAD
 #include <sys/types.h> /* For pid_t */
 #include "pythread.h"
-static long main_thread;
+static unsigned long main_thread;
 static pid_t main_pid;
 #endif
 
@@ -1088,7 +1088,7 @@
 /*[clinic input]
 signal.pthread_kill
 
-    thread_id:  long
+    thread_id:  unsigned_long(bitwise=True)
     signalnum:  int
     /
 
@@ -1096,8 +1096,9 @@
 [clinic start generated code]*/
 
 static PyObject *
-signal_pthread_kill_impl(PyObject *module, long thread_id, int signalnum)
-/*[clinic end generated code: output=2a09ce41f1c4228a input=77ed6a3b6f2a8122]*/
+signal_pthread_kill_impl(PyObject *module, unsigned long thread_id,
+                         int signalnum)
+/*[clinic end generated code: output=7629919b791bc27f input=1d901f2c7bb544ff]*/
 {
     int err;
 
diff --git a/Python/ceval.c b/Python/ceval.c
index fd60b73..e7ee772 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -148,7 +148,7 @@
 #include "pythread.h"
 
 static PyThread_type_lock pending_lock = 0; /* for pending calls */
-static long main_thread = 0;
+static unsigned long main_thread = 0;
 /* This single variable consolidates all requests to break out of the fast path
    in the eval loop. */
 static _Py_atomic_int eval_breaker = {0};
diff --git a/Python/import.c b/Python/import.c
index 0fc4d1d..17a320b 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -147,14 +147,14 @@
 #include "pythread.h"
 
 static PyThread_type_lock import_lock = 0;
-static long import_lock_thread = -1;
+static unsigned long import_lock_thread = PYTHREAD_INVALID_THREAD_ID;
 static int import_lock_level = 0;
 
 void
 _PyImport_AcquireLock(void)
 {
-    long me = PyThread_get_thread_ident();
-    if (me == -1)
+    unsigned long me = PyThread_get_thread_ident();
+    if (me == PYTHREAD_INVALID_THREAD_ID)
         return; /* Too bad */
     if (import_lock == NULL) {
         import_lock = PyThread_allocate_lock();
@@ -165,7 +165,8 @@
         import_lock_level++;
         return;
     }
-    if (import_lock_thread != -1 || !PyThread_acquire_lock(import_lock, 0))
+    if (import_lock_thread != PYTHREAD_INVALID_THREAD_ID ||
+        !PyThread_acquire_lock(import_lock, 0))
     {
         PyThreadState *tstate = PyEval_SaveThread();
         PyThread_acquire_lock(import_lock, 1);
@@ -179,15 +180,15 @@
 int
 _PyImport_ReleaseLock(void)
 {
-    long me = PyThread_get_thread_ident();
-    if (me == -1 || import_lock == NULL)
+    unsigned long me = PyThread_get_thread_ident();
+    if (me == PYTHREAD_INVALID_THREAD_ID || import_lock == NULL)
         return 0; /* Too bad */
     if (import_lock_thread != me)
         return -1;
     import_lock_level--;
     assert(import_lock_level >= 0);
     if (import_lock_level == 0) {
-        import_lock_thread = -1;
+        import_lock_thread = PYTHREAD_INVALID_THREAD_ID;
         PyThread_release_lock(import_lock);
     }
     return 1;
@@ -209,7 +210,7 @@
     }
     if (import_lock_level > 1) {
         /* Forked as a side effect of import */
-        long me = PyThread_get_thread_ident();
+        unsigned long me = PyThread_get_thread_ident();
         /* The following could fail if the lock is already held, but forking as
            a side-effect of an import is a) rare, b) nuts, and c) difficult to
            do thanks to the lock only being held when doing individual module
@@ -218,7 +219,7 @@
         import_lock_thread = me;
         import_lock_level--;
     } else {
-        import_lock_thread = -1;
+        import_lock_thread = PYTHREAD_INVALID_THREAD_ID;
         import_lock_level = 0;
     }
 }
@@ -238,7 +239,7 @@
 /*[clinic end generated code: output=8b89384b5e1963fc input=9b088f9b217d9bdf]*/
 {
 #ifdef WITH_THREAD
-    return PyBool_FromLong(import_lock_thread != -1);
+    return PyBool_FromLong(import_lock_thread != PYTHREAD_INVALID_THREAD_ID);
 #else
     Py_RETURN_FALSE;
 #endif
diff --git a/Python/pystate.c b/Python/pystate.c
index 65c244e..8e81707 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -580,7 +580,8 @@
    existing async exception.  This raises no exceptions. */
 
 int
-PyThreadState_SetAsyncExc(long id, PyObject *exc) {
+PyThreadState_SetAsyncExc(unsigned long id, PyObject *exc)
+{
     PyInterpreterState *interp = GET_INTERP_STATE();
     PyThreadState *p;
 
@@ -668,7 +669,7 @@
             struct _frame *frame = t->frame;
             if (frame == NULL)
                 continue;
-            id = PyLong_FromLong(t->thread_id);
+            id = PyLong_FromUnsignedLong(t->thread_id);
             if (id == NULL)
                 goto Fail;
             stat = PyDict_SetItem(result, id, (PyObject *)frame);
diff --git a/Python/thread.c b/Python/thread.c
index 63eeb1e..3a52e1e 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -172,7 +172,7 @@
     struct key *next;
 
     /* The thread id, according to PyThread_get_thread_ident(). */
-    long id;
+    unsigned long id;
 
     /* The key and its associated value. */
     int key;
@@ -208,7 +208,7 @@
 find_key(int set_value, int key, void *value)
 {
     struct key *p, *prev_p;
-    long id = PyThread_get_thread_ident();
+    unsigned long id = PyThread_get_thread_ident();
 
     if (!keymutex)
         return NULL;
@@ -312,7 +312,7 @@
 void
 PyThread_delete_key_value(int key)
 {
-    long id = PyThread_get_thread_ident();
+    unsigned long id = PyThread_get_thread_ident();
     struct key *p, **q;
 
     PyThread_acquire_lock(keymutex, 1);
@@ -338,7 +338,7 @@
 void
 PyThread_ReInitTLS(void)
 {
-    long id = PyThread_get_thread_ident();
+    unsigned long id = PyThread_get_thread_ident();
     struct key *p, **q;
 
     if (!keymutex)
diff --git a/Python/thread_foobar.h b/Python/thread_foobar.h
index ea96f9c..45cfd1b 100644
--- a/Python/thread_foobar.h
+++ b/Python/thread_foobar.h
@@ -9,7 +9,7 @@
 /*
  * Thread support.
  */
-long
+unsigned long
 PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
     int success = 0;            /* init not needed when SOLARIS_THREADS and */
@@ -18,10 +18,10 @@
     dprintf(("PyThread_start_new_thread called\n"));
     if (!initialized)
         PyThread_init_thread();
-    return success < 0 ? -1 : 0;
+    return success < 0 ? PYTHREAD_INVALID_THREAD_ID : 0;
 }
 
-long
+unsigned long
 PyThread_get_thread_ident(void)
 {
     if (!initialized)
diff --git a/Python/thread_nt.h b/Python/thread_nt.h
index 74a6ee8..8158ff8 100644
--- a/Python/thread_nt.h
+++ b/Python/thread_nt.h
@@ -140,7 +140,7 @@
 }
 #endif /* _PY_USE_CV_LOCKS */
 
-long PyThread_get_thread_ident(void);
+unsigned long PyThread_get_thread_ident(void);
 
 /*
  * Initialization of the C package, should not be needed.
@@ -172,21 +172,21 @@
     return 0;
 }
 
-long
+unsigned long
 PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
     HANDLE hThread;
     unsigned threadID;
     callobj *obj;
 
-    dprintf(("%ld: PyThread_start_new_thread called\n",
+    dprintf(("%lu: PyThread_start_new_thread called\n",
              PyThread_get_thread_ident()));
     if (!initialized)
         PyThread_init_thread();
 
     obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));
     if (!obj)
-        return -1;
+        return PYTHREAD_INVALID_THREAD_ID;
     obj->func = func;
     obj->arg = arg;
     hThread = (HANDLE)_beginthreadex(0,
@@ -199,24 +199,24 @@
          * too many threads".
          */
         int e = errno;
-        dprintf(("%ld: PyThread_start_new_thread failed, errno %d\n",
+        dprintf(("%lu: PyThread_start_new_thread failed, errno %d\n",
                  PyThread_get_thread_ident(), e));
         threadID = (unsigned)-1;
         HeapFree(GetProcessHeap(), 0, obj);
     }
     else {
-        dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n",
+        dprintf(("%lu: PyThread_start_new_thread succeeded: %p\n",
                  PyThread_get_thread_ident(), (void*)hThread));
         CloseHandle(hThread);
     }
-    return (long) threadID;
+    return threadID;
 }
 
 /*
  * Return the thread Id instead of a handle. The Id is said to uniquely identify the
  * thread in the system
  */
-long
+unsigned long
 PyThread_get_thread_ident(void)
 {
     if (!initialized)
@@ -228,7 +228,7 @@
 void
 PyThread_exit_thread(void)
 {
-    dprintf(("%ld: PyThread_exit_thread called\n", PyThread_get_thread_ident()));
+    dprintf(("%lu: PyThread_exit_thread called\n", PyThread_get_thread_ident()));
     if (!initialized)
         exit(0);
     _endthreadex(0);
@@ -250,7 +250,7 @@
 
     aLock = AllocNonRecursiveMutex() ;
 
-    dprintf(("%ld: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));
+    dprintf(("%lu: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));
 
     return (PyThread_type_lock) aLock;
 }
@@ -258,7 +258,7 @@
 void
 PyThread_free_lock(PyThread_type_lock aLock)
 {
-    dprintf(("%ld: PyThread_free_lock(%p) called\n", PyThread_get_thread_ident(),aLock));
+    dprintf(("%lu: PyThread_free_lock(%p) called\n", PyThread_get_thread_ident(),aLock));
 
     FreeNonRecursiveMutex(aLock) ;
 }
@@ -289,7 +289,7 @@
     else
         milliseconds = INFINITE;
 
-    dprintf(("%ld: PyThread_acquire_lock_timed(%p, %lld) called\n",
+    dprintf(("%lu: PyThread_acquire_lock_timed(%p, %lld) called\n",
              PyThread_get_thread_ident(), aLock, microseconds));
 
     if (aLock && EnterNonRecursiveMutex((PNRMUTEX)aLock,
@@ -300,7 +300,7 @@
         success = PY_LOCK_FAILURE;
     }
 
-    dprintf(("%ld: PyThread_acquire_lock(%p, %lld) -> %d\n",
+    dprintf(("%lu: PyThread_acquire_lock(%p, %lld) -> %d\n",
              PyThread_get_thread_ident(), aLock, microseconds, success));
 
     return success;
@@ -314,10 +314,10 @@
 void
 PyThread_release_lock(PyThread_type_lock aLock)
 {
-    dprintf(("%ld: PyThread_release_lock(%p) called\n", PyThread_get_thread_ident(),aLock));
+    dprintf(("%lu: PyThread_release_lock(%p) called\n", PyThread_get_thread_ident(),aLock));
 
     if (!(aLock && LeaveNonRecursiveMutex((PNRMUTEX) aLock)))
-        dprintf(("%ld: Could not PyThread_release_lock(%p) error: %ld\n", PyThread_get_thread_ident(), aLock, GetLastError()));
+        dprintf(("%lu: Could not PyThread_release_lock(%p) error: %ld\n", PyThread_get_thread_ident(), aLock, GetLastError()));
 }
 
 /* minimum/maximum thread stack sizes supported */
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index ba7393f..b95840c 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -184,7 +184,7 @@
  */
 
 
-long
+unsigned long
 PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
     pthread_t th;
@@ -202,7 +202,7 @@
 
 #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
     if (pthread_attr_init(&attrs) != 0)
-        return -1;
+        return PYTHREAD_INVALID_THREAD_ID;
 #endif
 #if defined(THREAD_STACK_SIZE)
     tss = (_pythread_stacksize != 0) ? _pythread_stacksize
@@ -210,7 +210,7 @@
     if (tss != 0) {
         if (pthread_attr_setstacksize(&attrs, tss) != 0) {
             pthread_attr_destroy(&attrs);
-            return -1;
+            return PYTHREAD_INVALID_THREAD_ID;
         }
     }
 #endif
@@ -232,31 +232,31 @@
     pthread_attr_destroy(&attrs);
 #endif
     if (status != 0)
-        return -1;
+        return PYTHREAD_INVALID_THREAD_ID;
 
     pthread_detach(th);
 
 #if SIZEOF_PTHREAD_T <= SIZEOF_LONG
-    return (long) th;
+    return (unsigned long) th;
 #else
-    return (long) *(long *) &th;
+    return (unsigned long) *(unsigned long *) &th;
 #endif
 }
 
 /* XXX This implementation is considered (to quote Tim Peters) "inherently
    hosed" because:
      - It does not guarantee the promise that a non-zero integer is returned.
-     - The cast to long is inherently unsafe.
+     - The cast to unsigned long is inherently unsafe.
      - It is not clear that the 'volatile' (for AIX?) are any longer necessary.
 */
-long
+unsigned long
 PyThread_get_thread_ident(void)
 {
     volatile pthread_t threadid;
     if (!initialized)
         PyThread_init_thread();
     threadid = pthread_self();
-    return (long) threadid;
+    return (unsigned long) threadid;
 }
 
 void
diff --git a/Python/traceback.c b/Python/traceback.c
index 9f8c568..b52385e 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -731,7 +731,7 @@
     else
         PUTS(fd, "Thread 0x");
     _Py_DumpHexadecimal(fd,
-                        (unsigned long)tstate->thread_id,
+                        tstate->thread_id,
                         sizeof(unsigned long) * 2);
     PUTS(fd, " (most recent call first):\n");
 }