diff --git a/mps/src/protsu.c b/mps/src/protsu.c
index a271a90da3e..d6d15377ffb 100644
--- a/mps/src/protsu.c
+++ b/mps/src/protsu.c
@@ -1,11 +1,7 @@
 /* impl.c.protsu: PROTECTION FOR SUNOS
  *
- * $HopeName: MMsrc!protsu.c(trunk.9) $
- * Copyright (C) 1995,1996,1997 Harlequin Group, all rights reserved
- *
- * READERSHIP
- *
- * .readership: Any MPS developer
+ * $HopeName: MMsrc!protsu.c(trunk.10) $
+ * Copyright (C) 1997 Harlequin Limited.  All rights reserved.
  *
  * DESIGN
  *
@@ -31,8 +27,9 @@
 
 #include <sys/mman.h>
 #include <signal.h>
+#include <limits.h>
 
-SRCID(protsu, "$HopeName: MMsrc!protsu.c(trunk.9) $");
+SRCID(protsu, "$HopeName: MMsrc!protsu.c(trunk.10) $");
 
 
 /* Fix up unprototyped system calls. */
@@ -215,8 +212,7 @@ void ProtSet(Addr base, Addr limit, AccessSet mode)
 }
 
 
-/* ProtSync -- synchronize protection settings with hardware
- */
+/* ProtSync -- synchronize protection settings with hardware */
 
 void ProtSync(Arena arena)
 {
@@ -226,8 +222,7 @@ void ProtSync(Arena arena)
 }
 
 
-/* ProtTramp -- protection trampoline
- */
+/* ProtTramp -- protection trampoline */
 
 void ProtTramp(void **resultReturn, void *(*f)(void *, size_t),
                void *p, size_t s)
diff --git a/mps/src/vmsu.c b/mps/src/vmsu.c
index 89c4b2fa0f7..50ab350b3c8 100644
--- a/mps/src/vmsu.c
+++ b/mps/src/vmsu.c
@@ -1,12 +1,9 @@
 /* impl.c.vmsu: VIRTUAL MEMORY MAPPING FOR SUNOS 4
  *
- * $HopeName: MMsrc!vmsu.c(trunk.19) $
+ * $HopeName: MMsrc!vmsu.c(trunk.20) $
  * Copyright (C) 1998 Harlequin Limited.  All rights reserved.
  *
- * Design: design.mps.vm
- *
- * This is the implementation of the virtual memory mapping interface
- * (vm.h) for SunOS 4.
+ * .design: See design.mps.vm for general design.
  *
  * mmap(2) is used to reserve address space by creating a mapping to
  * /etc/passwd with page access none.  mmap(2) is used to map pages
@@ -23,9 +20,9 @@
  *   in the address space, so that the limit of the mapped area
  *   is representable.
  *
- * .assume.size: The maximum size of the reserved address space
- *   is limited by the range of "int".  This will probably be half
- *   of the address space.
+ * .assume.size: The maximum size of the reserved address space is
+ *   limited by the range of "int" (because doc of munmap(2) says so).
+ *   This will probably be half of the address space.
  *
  * .assume.mmap.err: ENOMEM is the only error we really expect to
  *   get from mmap.  The others are either caused by invalid params
@@ -44,22 +41,18 @@
 #ifndef MPS_OS_SU
 #error "vmsu.c is SunOS 4 specific, but MPS_OS_SU is not set"
 #endif
-#ifdef VM_RM
-#error "vmsu.c compiled with VM_RM set"
-#endif /* VM_RM */
 
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <sys/errno.h>
+#include <limits.h>
 
-SRCID(vmsu, "$HopeName: MMsrc!vmsu.c(trunk.19) $");
+SRCID(vmsu, "$HopeName: MMsrc!vmsu.c(trunk.20) $");
 
 
-/* Fix up unprototyped system calls.  */
-/* Note that these are not fixed up by std.h because that only fixes */
-/* up discrepancies with ANSI. */
+/* Fix up unprototyped system calls. */
 
 extern int close(int fd);
 extern int munmap(caddr_t addr, int len);