diff --git a/distutils/command/build_ext.py b/distutils/command/build_ext.py
index f7ab32cfe1..22628baf90 100644
--- a/distutils/command/build_ext.py
+++ b/distutils/command/build_ext.py
@@ -220,7 +220,7 @@ def finalize_options(self):
         # For extensions under Cygwin, Python's library directory must be
         # appended to library_dirs
         if sys.platform[:6] == 'cygwin':
-            if sys.executable.startswith(os.path.join(sys.exec_prefix, "bin")):
+            if not sysconfig.python_build:
                 # building third party extensions
                 self.library_dirs.append(os.path.join(sys.prefix, "lib",
                                                       "python" + get_python_version(),