diff --git a/lib/libc/sys/shmat.2 b/lib/libc/sys/shmat.2
index 31e2a80d5091..b992d41a67ad 100644
--- a/lib/libc/sys/shmat.2
+++ b/lib/libc/sys/shmat.2
@@ -40,9 +40,9 @@
 .In sys/ipc.h
 .In sys/shm.h
 .Ft void *
-.Fn shmat "int shmid" "void *addr" "int flag"
+.Fn shmat "int shmid" "const void *addr" "int flag"
 .Ft int
-.Fn shmdt "void *addr"
+.Fn shmdt "const void *addr"
 .Sh DESCRIPTION
 The
 .Fn shmat
diff --git a/lib/libc/sys/shmget.2 b/lib/libc/sys/shmget.2
index e27ad0d3ce92..5d8bc5a9a179 100644
--- a/lib/libc/sys/shmget.2
+++ b/lib/libc/sys/shmget.2
@@ -39,7 +39,7 @@
 .In sys/ipc.h
 .In sys/shm.h
 .Ft int
-.Fn shmget "key_t key" "int size" "int flag"
+.Fn shmget "key_t key" "size_t size" "int flag"
 .Sh DESCRIPTION
 Based on the values of
 .Fa key
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index cd3e46892f7d..03c87946d124 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -361,11 +361,11 @@
 			    int msgflg); }
 227	MNOSTD	BSD	{ int msgrcv(int msqid, void *msgp, size_t msgsz, \
 			    long msgtyp, int msgflg); }
-228	MNOSTD	BSD	{ int shmat(int shmid, void *shmaddr, int shmflg); }
+228	MNOSTD	BSD	{ int shmat(int shmid, const void *shmaddr, int shmflg); }
 229	MNOSTD	BSD	{ int shmctl(int shmid, int cmd, \
 			    struct shmid_ds *buf); }
-230	MNOSTD	BSD	{ int shmdt(void *shmaddr); }
-231	MNOSTD	BSD	{ int shmget(key_t key, int size, int shmflg); }
+230	MNOSTD	BSD	{ int shmdt(const void *shmaddr); }
+231	MNOSTD	BSD	{ int shmget(key_t key, size_t size, int shmflg); }
 ;
 232	MSTD	POSIX	{ int clock_gettime(clockid_t clock_id, \
 			    struct timespec *tp); }
diff --git a/sys/kern/sysv_shm.c b/sys/kern/sysv_shm.c
index e04531094075..406e753a2fda 100644
--- a/sys/kern/sysv_shm.c
+++ b/sys/kern/sysv_shm.c
@@ -240,7 +240,7 @@ shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 
 #ifndef _SYS_SYSPROTO_H_
 struct shmdt_args {
-	void *shmaddr;
+	const void *shmaddr;
 };
 #endif
 
@@ -284,7 +284,7 @@ done2:
 #ifndef _SYS_SYSPROTO_H_
 struct shmat_args {
 	int shmid;
-	void *shmaddr;
+	const void *shmaddr;
 	int shmflg;
 };
 #endif
diff --git a/sys/sys/shm.h b/sys/sys/shm.h
index 6d66384bbaf6..a56e40d442d5 100644
--- a/sys/sys/shm.h
+++ b/sys/sys/shm.h
@@ -105,12 +105,17 @@ void	shmfork(struct proc *, struct proc *);
 
 #include <sys/cdefs.h>
 
+#ifndef _SIZE_T_DECLARED
+typedef __size_t        size_t;
+#define _SIZE_T_DECLARED
+#endif
+
 __BEGIN_DECLS
 int shmsys(int, ...);
-void *shmat(int, void *, int);
-int shmget(key_t, int, int);
+void *shmat(int, const void *, int);
+int shmget(key_t, size_t, int);
 int shmctl(int, int, struct shmid_ds *);
-int shmdt(void *);
+int shmdt(const void *);
 __END_DECLS
 
 #endif /* !_KERNEL */