Index: ConfigureChecks.cmake
--- ConfigureChecks.cmake.orig
+++ ConfigureChecks.cmake
@@ -109,7 +109,7 @@ check_c_source_compiles("
 __thread int tls;
 
 int main(void) {
-    return 0;
+    return tls;
 }" HAVE_GCC_THREAD_LOCAL_STORAGE)
 
 if (WIN32)
