diff --git a/src/c/threads_win32.d b/src/c/threads_win32.d
index 3b6984649..c4722c037 100644
--- a/src/c/threads_win32.d
+++ b/src/c/threads_win32.d
@@ -24,12 +24,12 @@
  * is designed to produce a DLL and we rather want a static
  * reference
  */
+#include <windows.h>
 #include <gc.h>
 extern HANDLE WINAPI GC_CreateThread(
     LPSECURITY_ATTRIBUTES lpThreadAttributes, 
     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress, 
     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId );
-
 #ifndef WITH___THREAD
 DWORD cl_env_key;
 #endif