diff --git a/bits.h b/bits.h
index 0121b97f..d8f8bd93 100644
--- a/bits.h
+++ b/bits.h
@@ -15,6 +15,7 @@
 #ifndef _BITS_H_
 #define _BITS_H_
 
+#include <sys/types.h>
 #include <stdint.h>
 
 /**