diff -urN a/setup.py b/setup.py
--- a/setup.py	2013-10-20 19:28:33.249888500 +0100
+++ b/setup.py	2013-10-20 19:28:56.054192900 +0100
@@ -1874,12 +1874,6 @@
             include_dirs.append('/usr/X11/include')
             added_lib_dirs.append('/usr/X11/lib')
 
-        # If Cygwin, then verify that X is installed before proceeding
-        if host_platform == 'cygwin':
-            x11_inc = find_file('X11/Xlib.h', [], include_dirs)
-            if x11_inc is None:
-                return
-
         # Check for BLT extension
         if self.compiler.find_library_file(lib_dirs + added_lib_dirs,
                                                'BLT8.0'):
@@ -1897,9 +1891,8 @@
         if host_platform in ['aix3', 'aix4']:
             libs.append('ld')
 
-        # Finally, link with the X11 libraries (not appropriate on cygwin)
-        if host_platform != "cygwin":
-            libs.append('X11')
+        # Finally, link with the X11 libraries
+        libs.append('X11')
 
         ext = Extension('_tkinter', ['_tkinter.c', 'tkappinit.c'],
                         define_macros=[('WITH_APPINIT', 1)] + defs,