diff --git a/include/villas/list.h b/include/villas/list.h
index aa674d25e..f186da293 100644
--- a/include/villas/list.h
+++ b/include/villas/list.h
@@ -14,6 +14,7 @@
 #pragma once
 
 #include <stdbool.h>
+#include <sys/types.h>
 #include <pthread.h>
 
 #include "common.h"