diff --git a/Doc/library/ctypes.rst b/Doc/library/ctypes.rst
index 582300c..f4c59f0 100644
--- a/Doc/library/ctypes.rst
+++ b/Doc/library/ctypes.rst
@@ -2248,6 +2248,11 @@ These are the fundamental ctypes data types:
    Represents the C :ctype:`size_t` datatype.
 
 
+.. class:: c_ssize_t
+
+    Represents the C :ctype:`ssize_t` datatype.
+
+
 .. class:: c_ubyte
 
    Represents the C :ctype:`unsigned char` datatype, it interprets the value as
diff --git a/Lib/ctypes/__init__.py b/Lib/ctypes/__init__.py
index 1b03835..16489b9 100644
--- a/Lib/ctypes/__init__.py
+++ b/Lib/ctypes/__init__.py
@@ -462,10 +462,13 @@ _pointer_type_cache[None] = c_void_p
 
 if sizeof(c_uint) == sizeof(c_void_p):
     c_size_t = c_uint
+    c_ssize_t = c_int
 elif sizeof(c_ulong) == sizeof(c_void_p):
     c_size_t = c_ulong
+    c_ssize_t = c_long
 elif sizeof(c_ulonglong) == sizeof(c_void_p):
     c_size_t = c_ulonglong
+    c_ssize_t = c_longlong
 
 # functions
 
diff --git a/Lib/ctypes/test/test_sizes.py b/Lib/ctypes/test/test_sizes.py
index 0509cbb..f9b5e97 100644
--- a/Lib/ctypes/test/test_sizes.py
+++ b/Lib/ctypes/test/test_sizes.py
@@ -1,8 +1,11 @@
 # Test specifically-sized containers.
 
-import unittest
 from ctypes import *
 
+import sys
+import unittest
+
+
 class SizesTestCase(unittest.TestCase):
     def test_8(self):
         self.assertEqual(1, sizeof(c_int8))
@@ -23,5 +26,9 @@ class SizesTestCase(unittest.TestCase):
     def test_size_t(self):
         self.assertEqual(sizeof(c_void_p), sizeof(c_size_t))
 
+    def test_ssize_t(self):
+        self.assertEqual(sizeof(c_void_p), sizeof(c_ssize_t))
+
+
 if __name__ == "__main__":
     unittest.main()