diff -r 5a58f6e793cc Modules/clinic/binascii.c.h
--- a/Modules/clinic/binascii.c.h	Tue Aug 05 08:14:59 2014 +0300
+++ b/Modules/clinic/binascii.c.h	Tue Aug 05 16:19:56 2014 +1000
@@ -320,7 +320,7 @@
         &data, &crc))
         goto exit;
     _return_value = binascii_crc32_impl(module, &data, crc);
-    if ((_return_value == -1) && PyErr_Occurred())
+    if ((_return_value == (unsigned int)-1) && PyErr_Occurred())
         goto exit;
     return_value = PyLong_FromUnsignedLong((unsigned long)_return_value);
 
@@ -475,4 +475,4 @@
 
     return return_value;
 }
-/*[clinic end generated code: output=68e2bcc6956b6213 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=53cd6b379c745220 input=a9049054013a1b77]*/
diff -r 5a58f6e793cc Modules/posixmodule.c
--- a/Modules/posixmodule.c	Tue Aug 05 08:14:59 2014 +0300
+++ b/Modules/posixmodule.c	Tue Aug 05 16:19:56 2014 +1000
@@ -12466,7 +12466,7 @@
         &device))
         goto exit;
     _return_value = os_major_impl(module, device);
-    if ((_return_value == -1) && PyErr_Occurred())
+    if ((_return_value == (unsigned int)-1) && PyErr_Occurred())
         goto exit;
     return_value = PyLong_FromUnsignedLong((unsigned long)_return_value);
 
@@ -12476,7 +12476,7 @@
 
 static unsigned int
 os_major_impl(PyModuleDef *module, int device)
-/*[clinic end generated code: output=f60d3cc3d5d20325 input=ea48820b7e10d310]*/
+/*[clinic end generated code: output=52e6743300dcf4ad input=ea48820b7e10d310]*/
 {
     return major(device);
 }
@@ -12515,7 +12515,7 @@
         &device))
         goto exit;
     _return_value = os_minor_impl(module, device);
-    if ((_return_value == -1) && PyErr_Occurred())
+    if ((_return_value == (unsigned int)-1) && PyErr_Occurred())
         goto exit;
     return_value = PyLong_FromUnsignedLong((unsigned long)_return_value);
 
@@ -12525,7 +12525,7 @@
 
 static unsigned int
 os_minor_impl(PyModuleDef *module, int device)
-/*[clinic end generated code: output=71eca1d5149c2a07 input=089733ebbf9754e8]*/
+/*[clinic end generated code: output=aebe4bd7f455b755 input=089733ebbf9754e8]*/
 {
     return minor(device);
 }
@@ -12566,7 +12566,7 @@
         &major, &minor))
         goto exit;
     _return_value = os_makedev_impl(module, major, minor);
-    if ((_return_value == -1) && PyErr_Occurred())
+    if ((_return_value == (unsigned int)-1) && PyErr_Occurred())
         goto exit;
     return_value = PyLong_FromUnsignedLong((unsigned long)_return_value);
 
@@ -12576,7 +12576,7 @@
 
 static unsigned int
 os_makedev_impl(PyModuleDef *module, int major, int minor)
-/*[clinic end generated code: output=e04dc5723a98cd3b input=f55bf7cffb028a08]*/
+/*[clinic end generated code: output=5cb79d9c9eac58b0 input=f55bf7cffb028a08]*/
 {
     return makedev(major, minor);
 }
diff -r 5a58f6e793cc Tools/clinic/clinic.py
--- a/Tools/clinic/clinic.py	Tue Aug 05 08:14:59 2014 +0300
+++ b/Tools/clinic/clinic.py	Tue Aug 05 16:19:56 2014 +1000
@@ -2865,10 +2865,11 @@
     type = 'long'
     conversion_fn = 'PyLong_FromLong'
     cast = ''
+    unsigned_cast = ''
 
     def render(self, function, data):
         self.declare(data)
-        self.err_occurred_if("_return_value == -1", data)
+        self.err_occurred_if("_return_value == {}-1".format(self.unsigned_cast), data)
         data.return_conversion.append(
             ''.join(('return_value = ', self.conversion_fn, '(', self.cast, '_return_value);\n')))
 
@@ -2889,10 +2890,12 @@
 class unsigned_long_return_converter(long_return_converter):
     type = 'unsigned long'
     conversion_fn = 'PyLong_FromUnsignedLong'
+    unsigned_cast = '(unsigned long)'
 
 class unsigned_int_return_converter(unsigned_long_return_converter):
     type = 'unsigned int'
     cast = '(unsigned long)'
+    unsigned_cast = '(unsigned int)'
 
 class Py_ssize_t_return_converter(long_return_converter):
     type = 'Py_ssize_t'
@@ -2901,6 +2904,7 @@
 class size_t_return_converter(long_return_converter):
     type = 'size_t'
     conversion_fn = 'PyLong_FromSize_t'
+    unsigned_cast = '(size_t)'
 
 
 class double_return_converter(CReturnConverter):