diff --git a/source/io/TlsOptions.cpp b/source/io/TlsOptions.cpp
--- a/source/io/TlsOptions.cpp	(revision 9ef58ff20df19e613c91c5f761e381c763da6810)
+++ b/source/io/TlsOptions.cpp	(date 1635309758483)
@@ -90,7 +90,7 @@
                 return ctxOptions;
             }
 #endif /* !AWS_OS_IOS */
-#if defined(AWS_OS_APPLE)
+#if defined(AWS_OS_MACOS)
             TlsContextOptions TlsContextOptions::InitClientWithMtlsPkcs12(
                 const char *pkcs12Path,
                 const char *pkcs12Pwd,
@@ -111,7 +111,7 @@
                 AWS_ASSERT(m_isInit);
                 return aws_tls_ctx_options_set_keychain_path(&m_options, &keychain_path) == 0;
             }
-#endif /* AWS_OS_APPLE */
+#endif /* AWS_OS_MACOS */
 
 #ifdef _WIN32
             TlsContextOptions TlsContextOptions::InitClientWithMtlsSystemPath(