diff --git a/conf/check_thread_storage.c b/conf/check_thread_storage.c
index e6e1e98..ed5510f 100644
--- a/conf/check_thread_storage.c
+++ b/conf/check_thread_storage.c
@@ -1,4 +1,4 @@
-extern __thread int x;
+extern __declspec(thread) int x;
 
 int main(int argc, char **argv) {
   return 0;