diff --git a/minix/include/minix/drivers.h b/minix/include/minix/drivers.h
index da94fef..80e381c 100644
--- a/minix/include/minix/drivers.h
+++ b/minix/include/minix/drivers.h
@@ -9,6 +9,9 @@
 #define _NETBSD_SOURCE	1	/* tell headers to include MINIX stuff */
 #define _SYSTEM		1	/* get negative error number in <errno.h> */
 
+#include <sys/types.h>
+#include <limits.h>
+
 /* The following are so basic, all the *.c files get them automatically. */
 #include <minix/config.h>	/* MUST be first */
 #include <minix/bitmap.h>