diff --git a/sys/posix4/sched.h b/sys/posix4/sched.h
index b8b6bd2e8158..92fad6da914d 100644
--- a/sys/posix4/sched.h
+++ b/sys/posix4/sched.h
@@ -38,10 +38,11 @@
 #ifndef _SCHED_H_
 #define _SCHED_H_
 
-#include <sys/types.h>	/* For pid_t */
+#include <sys/_types.h>
 
-#ifndef _KERNEL
-#include <time.h>		/* Per P1003.4 */
+#ifndef _PID_T_DECLARED
+typedef	__pid_t		pid_t;
+#define	_PID_T_DECLARED
 #endif
 
 /*
@@ -58,6 +59,8 @@ struct sched_param {
 #ifndef _KERNEL
 #include <sys/cdefs.h>
 
+struct timespec;
+
 __BEGIN_DECLS
 int	sched_get_priority_max(int);
 int	sched_get_priority_min(int);