Don't assume that os.confstr_names exists.
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index fe2a228..557f04d 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -17,7 +17,8 @@
# and unmaintained) linuxthreads threading library. There's an issue
# when combining linuxthreads with a failed execv call: see
# http://bugs.python.org/issue4970.
-if "CS_GNU_LIBPTHREAD_VERSION" in os.confstr_names:
+if (hasattr(os, "confstr_names") and
+ "CS_GNU_LIBPTHREAD_VERSION" in os.confstr_names):
libpthread = os.confstr("CS_GNU_LIBPTHREAD_VERSION")
USING_LINUXTHREADS= libpthread.startswith("linuxthreads")
else: