diff --git a/libctru/include/3ds/synchronization.h b/libctru/include/3ds/synchronization.h
index f23594b..d09bc7f 100644
--- a/libctru/include/3ds/synchronization.h
+++ b/libctru/include/3ds/synchronization.h
@@ -4,6 +4,7 @@
  */
 #pragma once
 #include <sys/lock.h>
+#include <3ds/svc.h>
 
 /// A light lock.
 typedef _LOCK_T LightLock;