no need for None
diff --git a/src/_cffi_src/build_openssl.py b/src/_cffi_src/build_openssl.py
index bd8cf73..49d7464 100644
--- a/src/_cffi_src/build_openssl.py
+++ b/src/_cffi_src/build_openssl.py
@@ -14,7 +14,7 @@
     # OpenSSL goes by a different library name on different operating systems.
     if platform == "darwin":
         return _osx_libraries(
-            os.environ.get("CRYPTOGRAPHY_BUILD_STATIC", None)
+            os.environ.get("CRYPTOGRAPHY_BUILD_STATIC")
         )
     elif platform == "win32":
         return ["libeay32", "ssleay32", "advapi32",