diff --git a/lib/connect.c b/lib/connect.c
index 0f7deb3cb..5a376c34a 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -921,7 +921,8 @@ void Curl_sndbufset(curl_socket_t sockfd)
   static int detectOsState = DETECT_OS_NONE;
 
   if(detectOsState == DETECT_OS_NONE) {
-#if (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
+#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
+    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
     OSVERSIONINFO osver;
 
     memset(&osver, 0, sizeof(osver));
diff --git a/lib/curl_sspi.c b/lib/curl_sspi.c
index 1cc18877f..bb41a879c 100644
--- a/lib/curl_sspi.c
+++ b/lib/curl_sspi.c
@@ -79,7 +79,8 @@ CURLcode Curl_sspi_global_init(void)
     DWORD majorVersion = 4;
     DWORD platformId = VER_PLATFORM_WIN32_NT;
 
-#if (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
+#if !defined(_WIN32_WINNT) || !defined(_WIN32_WINNT_WIN2K) || \
+    (_WIN32_WINNT < _WIN32_WINNT_WIN2K)
     OSVERSIONINFO osver;
 
     memset(&osver, 0, sizeof(osver));