Include SDL_hint.h.
diff --git a/src/thread/pthread/SDL_systhread.c b/src/thread/pthread/SDL_systhread.c
index 2dc6024..73a0120 100644
--- a/src/thread/pthread/SDL_systhread.c
+++ b/src/thread/pthread/SDL_systhread.c
@@ -21,6 +21,7 @@
#include "../../SDL_internal.h"
#include "SDL_system.h"
+#include "SDL_hint.h"
#include <pthread.h>