diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 91dcd04..909e0ab 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -600,6 +600,48 @@
     class Win32ErrorTests(unittest.TestCase):
         pass
 
+    class PosixUidGidTests(unittest.TestCase):
+        if hasattr(os, 'setuid'):
+            def test_setuid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.setuid, 0)
+                self.assertRaises(OverflowError, os.setuid, 1<<32)
+
+        if hasattr(os, 'setgid'):
+            def test_setgid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.setgid, 0)
+                self.assertRaises(OverflowError, os.setgid, 1<<32)
+
+        if hasattr(os, 'seteuid'):
+            def test_seteuid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.seteuid, 0)
+                self.assertRaises(OverflowError, os.seteuid, 1<<32)
+
+        if hasattr(os, 'setegid'):
+            def test_setegid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.setegid, 0)
+                self.assertRaises(OverflowError, os.setegid, 1<<32)
+
+        if hasattr(os, 'setreuid'):
+            def test_setreuid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.setreuid, 0, 0)
+                self.assertRaises(OverflowError, os.setreuid, 1<<32, 0)
+                self.assertRaises(OverflowError, os.setreuid, 0, 1<<32)
+
+        if hasattr(os, 'setregid'):
+            def test_setregid(self):
+                if os.getuid() != 0:
+                    self.assertRaises(os.error, os.setregid, 0, 0)
+                self.assertRaises(OverflowError, os.setregid, 1<<32, 0)
+                self.assertRaises(OverflowError, os.setregid, 0, 1<<32)
+else:
+    class PosixUidGidTests(unittest.TestCase):
+        pass
+
 def test_main():
     test_support.run_unittest(
         FileTests,
@@ -611,7 +653,8 @@
         DevNullTests,
         URandomTests,
         Win32ErrorTests,
-        TestInvalidFD
+        TestInvalidFD,
+        PosixUidGidTests
     )
 
 if __name__ == "__main__":
diff --git a/Misc/NEWS b/Misc/NEWS
index 25163b9..bf0eec8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -97,6 +97,9 @@
 - Issue #3845: In PyRun_SimpleFileExFlags avoid invalid memory access with
   short file names.
 
+- Issue #5705: os.setuid() would not accept values > 2**31-1 but pwd.getpwnam()
+  returned them on 64bit platforms.
+
 Library
 -------
 
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 5858b4a..f355cf6 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -5505,9 +5505,15 @@
 static PyObject *
 posix_setuid(PyObject *self, PyObject *args)
 {
-	int uid;
-	if (!PyArg_ParseTuple(args, "i:setuid", &uid))
+	long uid_arg;
+	uid_t uid;
+	if (!PyArg_ParseTuple(args, "l:setuid", &uid_arg))
 		return NULL;
+	uid = uid_arg;
+	if (uid != uid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "user id too big");
+		return NULL;
+	}
 	if (setuid(uid) < 0)
 		return posix_error();
 	Py_INCREF(Py_None);
@@ -5524,10 +5530,16 @@
 static PyObject *
 posix_seteuid (PyObject *self, PyObject *args)
 {
-	int euid;
-	if (!PyArg_ParseTuple(args, "i", &euid)) {
+	long euid_arg;
+	uid_t euid;
+	if (!PyArg_ParseTuple(args, "l", &euid_arg))
 		return NULL;
-	} else if (seteuid(euid) < 0) {
+	euid = euid_arg;
+	if (euid != euid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "user id too big");
+		return NULL;
+	}
+	if (seteuid(euid) < 0) {
 		return posix_error();
 	} else {
 		Py_INCREF(Py_None);
@@ -5544,10 +5556,16 @@
 static PyObject *
 posix_setegid (PyObject *self, PyObject *args)
 {
-	int egid;
-	if (!PyArg_ParseTuple(args, "i", &egid)) {
+	long egid_arg;
+	gid_t egid;
+	if (!PyArg_ParseTuple(args, "l", &egid_arg))
 		return NULL;
-	} else if (setegid(egid) < 0) {
+	egid = egid_arg;
+	if (egid != egid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "group id too big");
+		return NULL;
+	}
+	if (setegid(egid) < 0) {
 		return posix_error();
 	} else {
 		Py_INCREF(Py_None);
@@ -5564,10 +5582,17 @@
 static PyObject *
 posix_setreuid (PyObject *self, PyObject *args)
 {
-	int ruid, euid;
-	if (!PyArg_ParseTuple(args, "ii", &ruid, &euid)) {
+	long ruid_arg, euid_arg;
+	uid_t ruid, euid;
+	if (!PyArg_ParseTuple(args, "ll", &ruid_arg, &euid_arg))
 		return NULL;
-	} else if (setreuid(ruid, euid) < 0) {
+	ruid = ruid_arg;
+	euid = euid_arg;
+	if (euid != euid_arg || ruid != ruid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "user id too big");
+		return NULL;
+	}
+	if (setreuid(ruid, euid) < 0) {
 		return posix_error();
 	} else {
 		Py_INCREF(Py_None);
@@ -5584,10 +5609,17 @@
 static PyObject *
 posix_setregid (PyObject *self, PyObject *args)
 {
-	int rgid, egid;
-	if (!PyArg_ParseTuple(args, "ii", &rgid, &egid)) {
+	long rgid_arg, egid_arg;
+	gid_t rgid, egid;
+	if (!PyArg_ParseTuple(args, "ll", &rgid_arg, &egid_arg))
 		return NULL;
-	} else if (setregid(rgid, egid) < 0) {
+	rgid = rgid_arg;
+	egid = egid_arg;
+	if (egid != egid_arg || rgid != rgid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "group id too big");
+		return NULL;
+	}
+	if (setregid(rgid, egid) < 0) {
 		return posix_error();
 	} else {
 		Py_INCREF(Py_None);
@@ -5604,9 +5636,15 @@
 static PyObject *
 posix_setgid(PyObject *self, PyObject *args)
 {
-	int gid;
-	if (!PyArg_ParseTuple(args, "i:setgid", &gid))
+	long gid_arg;
+	gid_t gid;
+	if (!PyArg_ParseTuple(args, "l:setgid", &gid_arg))
 		return NULL;
+	gid = gid_arg;
+	if (gid != gid_arg) {
+		PyErr_SetString(PyExc_OverflowError, "group id too big");
+		return NULL;
+	}
 	if (setgid(gid) < 0)
 		return posix_error();
 	Py_INCREF(Py_None);
@@ -5654,7 +5692,7 @@
 					return NULL;
 				}
 				grouplist[i] = x;
-				/* read back the value to see if it fitted in gid_t */
+				/* read back to see if it fits in gid_t */
 				if (grouplist[i] != x) {
 					PyErr_SetString(PyExc_TypeError,
 							"group id too big");