diff --git a/Lib/distutils/command/build_ext.py b/Lib/distutils/command/build_ext.py
index ad3caf86529fb1..b46ae085afc12d 100644
--- a/Lib/distutils/command/build_ext.py
+++ b/Lib/distutils/command/build_ext.py
@@ -219,7 +219,7 @@ def finalize_options(self):
         # For extensions under Cygwin, Python's library directory must be
         # appended to library_dirs
         if sys.platform[:6] == 'cygwin' or self.plat_name.startswith(('mingw')):
-            if sys.executable.startswith(os.path.join(sys.exec_prefix, "bin")):
+            if not sysconfig.python_build:
                 # building third party extensions
                 config_dir_name = os.path.basename(sysconfig.get_config_var('LIBPL'))
                 self.library_dirs.append(os.path.join(sys.prefix, "lib",