diff --git a/include/minix/com.h b/include/minix/com.h
index c2823b693..be76f37b0 100644
--- a/include/minix/com.h
+++ b/include/minix/com.h
@@ -312,16 +312,6 @@
 
 #define CP_FLAG_TRY	0x01	/* do not transparently map */
 
-/* Field names for SYS_VUMAP. */
-#define VUMAP_ENDPT	m10_i1	/* grant owner, or SELF for local addresses */
-#define VUMAP_VADDR	m10_l1	/* address of virtual (input) vector */
-#define VUMAP_VCOUNT	m10_i2	/* number of elements in virtual vector */
-#define VUMAP_OFFSET	m10_l2	/* offset into first entry of input vector */
-#define VUMAP_ACCESS	m10_i3	/* access requested for input (VUA_ flags) */
-#define VUMAP_PADDR	m10_l3	/* address of physical (output) vector */
-#define VUMAP_PMAX	m10_i4	/* max number of physical vector elements */
-#define VUMAP_PCOUNT	m10_i1	/* upon return: number of elements filled */
-
 /* Field names for SYS_GETINFO. */
 #define I_REQUEST      m7_i3	/* what info to get */
 #   define GET_KINFO	   0	/* get kernel information structure */
diff --git a/include/minix/ipc.h b/include/minix/ipc.h
index edaa36bd1..affeab133 100644
--- a/include/minix/ipc.h
+++ b/include/minix/ipc.h
@@ -791,6 +791,26 @@ typedef struct {
 } mess_lsys_krn_sys_vdevio;
 _ASSERT_MSG_SIZE(mess_lsys_krn_sys_vdevio);
 
+typedef struct {
+	endpoint_t endpt;
+	vir_bytes vaddr;			/* struct vumap_vir * */
+	int vcount;
+	vir_bytes paddr;			/* struct vumap_phys * */
+	int pmax;
+	int access;
+	size_t offset;
+
+	uint8_t padding[28];
+} mess_lsys_krn_sys_vumap;
+_ASSERT_MSG_SIZE(mess_lsys_krn_sys_vumap);
+
+typedef struct {
+	int pcount;
+
+	uint8_t padding[52];
+} mess_krn_lsys_sys_vumap;
+_ASSERT_MSG_SIZE(mess_krn_lsys_sys_vumap);
+
 typedef struct {
 	phys_bytes base;
 	phys_bytes count;
@@ -1450,6 +1470,7 @@ typedef struct {
 		mess_krn_lsys_schedule	m_krn_lsys_schedule;
 		mess_krn_lsys_sys_irqctl m_krn_lsys_sys_irqctl;
 		mess_krn_lsys_sys_umap	m_krn_lsys_sys_umap;
+		mess_krn_lsys_sys_vumap	m_krn_lsys_sys_vumap;
 
 		mess_fs_vfs_breadwrite	m_fs_vfs_breadwrite;
 		mess_fs_vfs_chmod	m_fs_vfs_chmod;
@@ -1535,6 +1556,7 @@ typedef struct {
 		mess_lsys_krn_sys_setalarm m_lsys_krn_sys_setalarm;
 		mess_lsys_krn_sys_umap	m_lsys_krn_sys_umap;
 		mess_lsys_krn_sys_vdevio m_lsys_krn_sys_vdevio;
+		mess_lsys_krn_sys_vumap m_lsys_krn_sys_vumap;
 
 		mess_lsys_pci_busc_get_bar m_lsys_pci_busc_get_bar;
 
diff --git a/kernel/system/do_vumap.c b/kernel/system/do_vumap.c
index e3fc3152b..47bc35edb 100644
--- a/kernel/system/do_vumap.c
+++ b/kernel/system/do_vumap.c
@@ -2,14 +2,14 @@
  *   m_type:	SYS_VUMAP
  *
  * The parameters for this kernel call are:
- *   m10_i1:	VUMAP_ENDPT	(grant owner, or SELF for local addresses)
- *   m10_l1:	VUMAP_VADDR	(address of virtual (input) vector)
- *   m10_i2:	VUMAP_VCOUNT	(number of elements in virtual vector)
- *   m10_l2:	VUMAP_OFFSET	(offset into first entry of input vector)
- *   m10_i3:	VUMAP_ACCESS	(safecopy access requested for input)
- *   m10_l3:	VUMAP_PADDR	(address of physical (output) vector)
- *   m10_i4:	VUMAP_PMAX	(maximum number of physical vector elements)
- *   m10_i1:	VUMAP_PCOUNT	(upon return: number of elements filled)
+ *   m_lsys_krn_sys_vumap.endpt		(grant owner, or SELF for local addresses)
+ *   m_lsys_krn_sys_vumap.vaddr		(address of virtual (input) vector)
+ *   m_lsys_krn_sys_vumap.vcount	(number of elements in virtual vector)
+ *   m_lsys_krn_sys_vumap.offset	(offset into first entry of input vector)
+ *   m_lsys_krn_sys_vumap.access	(safecopy access requested for input)
+ *   m_lsys_krn_sys_vumap.paddr		(address of physical (output) vector)
+ *   m_lsys_krn_sys_vumap.pmax		(maximum number of physical vector elements)
+ *   m_krn_lsys_sys_vumap.pcount	(upon return: number of elements filled)
  */
 
 #include "kernel/system.h"
@@ -37,13 +37,13 @@ int do_vumap(struct proc *caller, message *m_ptr)
   endpt = caller->p_endpoint;
 
   /* Retrieve and check input parameters. */
-  source = m_ptr->VUMAP_ENDPT;
-  vaddr = (vir_bytes) m_ptr->VUMAP_VADDR;
-  vcount = m_ptr->VUMAP_VCOUNT;
-  offset = m_ptr->VUMAP_OFFSET;
-  access = m_ptr->VUMAP_ACCESS;
-  paddr = (vir_bytes) m_ptr->VUMAP_PADDR;
-  pmax = m_ptr->VUMAP_PMAX;
+  source = m_ptr->m_lsys_krn_sys_vumap.endpt;
+  vaddr = m_ptr->m_lsys_krn_sys_vumap.vaddr;
+  vcount = m_ptr->m_lsys_krn_sys_vumap.vcount;
+  offset = m_ptr->m_lsys_krn_sys_vumap.offset;
+  access = m_ptr->m_lsys_krn_sys_vumap.access;
+  paddr = m_ptr->m_lsys_krn_sys_vumap.paddr;
+  pmax = m_ptr->m_lsys_krn_sys_vumap.pmax;
 
   if (vcount <= 0 || pmax <= 0)
 	return EINVAL;
@@ -125,7 +125,7 @@ int do_vumap(struct proc *caller, message *m_ptr)
   r = data_copy_vmcheck(caller, KERNEL, (vir_bytes) pvec, endpt, paddr, size);
 
   if (r == OK)
-	m_ptr->VUMAP_PCOUNT = pcount;
+	m_ptr->m_krn_lsys_sys_vumap.pcount = pcount;
 
   return r;
 }
diff --git a/lib/libsys/sys_vumap.c b/lib/libsys/sys_vumap.c
index a84555180..b1b56b449 100644
--- a/lib/libsys/sys_vumap.c
+++ b/lib/libsys/sys_vumap.c
@@ -16,19 +16,19 @@ int sys_vumap(
   message m;
   int r;
 
-  m.VUMAP_ENDPT = endpt;
-  m.VUMAP_VADDR = (vir_bytes) vvec;
-  m.VUMAP_VCOUNT = vcount;
-  m.VUMAP_OFFSET = offset;
-  m.VUMAP_ACCESS = access;
-  m.VUMAP_PADDR = (vir_bytes) pvec;
-  m.VUMAP_PMAX = *pcount;
+  m.m_lsys_krn_sys_vumap.endpt = endpt;
+  m.m_lsys_krn_sys_vumap.vaddr = (vir_bytes) vvec;
+  m.m_lsys_krn_sys_vumap.vcount = vcount;
+  m.m_lsys_krn_sys_vumap.offset = offset;
+  m.m_lsys_krn_sys_vumap.access = access;
+  m.m_lsys_krn_sys_vumap.paddr = (vir_bytes) pvec;
+  m.m_lsys_krn_sys_vumap.pmax = *pcount;
 
   r = _kernel_call(SYS_VUMAP, &m);
 
   if (r != OK)
 	return r;
 
-  *pcount = m.VUMAP_PCOUNT;
+  *pcount = m.m_krn_lsys_sys_vumap.pcount;
   return OK;
 }