diff --git a/include/minix/com.h b/include/minix/com.h
index 12b01271f..c2823b693 100644
--- a/include/minix/com.h
+++ b/include/minix/com.h
@@ -310,18 +310,8 @@
 #  define IRQ_WORD      0x200	/* word values */
 #  define IRQ_LONG      0x400	/* long values */
 
-/* Field names for _UMAP, _VIRCOPY, _PHYSCOPY. */
-#define CP_SRC_ENDPT	m5_i1	/* process to copy from */
-#define CP_SRC_ADDR	m5_l1	/* address where data come from */
-#define CP_DST_ENDPT	m5_i2	/* process to copy to */
-#define CP_DST_ADDR	m5_l2	/* address where data go to */
-#define CP_NR_BYTES	m5_l3	/* number of bytes to copy */
-#define CP_FLAGS	m5_s2	/* number of bytes to copy */
-
 #define CP_FLAG_TRY	0x01	/* do not transparently map */
 
-#define UMAP_SEG 	m5_s1
-
 /* 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 */
diff --git a/include/minix/ipc.h b/include/minix/ipc.h
index 5978b4eed..edaa36bd1 100644
--- a/include/minix/ipc.h
+++ b/include/minix/ipc.h
@@ -764,6 +764,24 @@ typedef struct {
 } mess_lsys_krn_sys_setalarm;
 _ASSERT_MSG_SIZE(mess_lsys_krn_sys_setalarm);
 
+typedef struct {
+	endpoint_t src_endpt;
+	int segment;
+	vir_bytes src_addr;
+	endpoint_t dst_endpt;
+	int nr_bytes;
+
+	uint8_t padding[36];
+} mess_lsys_krn_sys_umap;
+_ASSERT_MSG_SIZE(mess_lsys_krn_sys_umap);
+
+typedef struct {
+	phys_bytes dst_addr;
+
+	uint8_t padding[52];
+} mess_krn_lsys_sys_umap;
+_ASSERT_MSG_SIZE(mess_krn_lsys_sys_umap);
+
 typedef struct {
 	int request;
 	int vec_size;
@@ -1431,6 +1449,7 @@ 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_fs_vfs_breadwrite	m_fs_vfs_breadwrite;
 		mess_fs_vfs_chmod	m_fs_vfs_chmod;
@@ -1514,6 +1533,7 @@ typedef struct {
 		mess_lsys_krn_sys_memset m_lsys_krn_sys_memset;
 		mess_lsys_krn_sys_sdevio m_lsys_krn_sys_sdevio;
 		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_pci_busc_get_bar m_lsys_pci_busc_get_bar;
diff --git a/kernel/system/do_umap.c b/kernel/system/do_umap.c
index 32c1ff3a8..9c0128bf9 100755
--- a/kernel/system/do_umap.c
+++ b/kernel/system/do_umap.c
@@ -2,11 +2,11 @@
  *   m_type:	SYS_UMAP
  *
  * The parameters for this kernel call are:
- *    m5_i1:	CP_SRC_PROC_NR	(process number)
- *    m5_s1:	UMAP_SEG	(segment where address is: T, D, or S)
- *    m5_l1:	CP_SRC_ADDR	(virtual address)
- *    m5_l2:	CP_DST_ADDR	(returns physical address)
- *    m5_l3:	CP_NR_BYTES	(size of datastructure)
+ *   m_lsys_krn_sys_umap.src_endpt	(process number)
+ *   m_lsys_krn_sys_umap.segment	(segment where address is: T, D, or S)
+ *   m_lsys_krn_sys_umap.src_addr	(virtual address)
+ *   m_krn_lsys_sys_umap.dst_addr	(returns physical address)
+ *   m_lsys_krn_sys_umap.nr_bytes	(size of datastructure)
  */
 
 #include "kernel/system.h"
@@ -24,15 +24,15 @@
  *==========================================================================*/
 int do_umap(struct proc * caller, message * m_ptr)
 {
-  int seg_index = m_ptr->UMAP_SEG & SEGMENT_INDEX;
-  int endpt = (int) m_ptr->CP_SRC_ENDPT;
+  int seg_index = m_ptr->m_lsys_krn_sys_umap.segment & SEGMENT_INDEX;
+  int endpt = m_ptr->m_lsys_krn_sys_umap.src_endpt;
 
   /* This call is a subset of umap_remote, it allows mapping virtual addresses
    * in the caller's address space and grants where the caller is specified as
    * grantee; after the security check we simply invoke do_umap_remote
    */
   if (seg_index != MEM_GRANT && endpt != SELF) return EPERM;
-  m_ptr->CP_DST_ENDPT = SELF;
+  m_ptr->m_lsys_krn_sys_umap.dst_endpt = SELF;
   return do_umap_remote(caller, m_ptr);
 }
 
diff --git a/kernel/system/do_umap_remote.c b/kernel/system/do_umap_remote.c
index 7e9c10fc1..8ebe78d28 100644
--- a/kernel/system/do_umap_remote.c
+++ b/kernel/system/do_umap_remote.c
@@ -2,12 +2,12 @@
  *   m_type:	SYS_UMAP_REMOTE
  *
  * The parameters for this kernel call are:
- *    m5_i1:	CP_SRC_PROC_NR	(process number)
- *    m5_s1:	UMAP_SEG	(segment where address is: T, D, or S)
- *    m5_l1:	CP_SRC_ADDR	(virtual address)
- *    m5_i2:	CP_DST_ENDPT	(process number of grantee to check access for)
- *    m5_l2:	CP_DST_ADDR	(returns physical address)
- *    m5_l3:	CP_NR_BYTES	(size of datastructure)
+ *   m_lsys_krn_sys_umap.src_endpt	(process number)
+ *   m_lsys_krn_sys_umap.segment	(segment where address is: T, D, or S)
+ *   m_lsys_krn_sys_umap.src_addr	(virtual address)
+ *   m_lsys_krn_sys_umap.dst_endpt	(process number of grantee to check access for)
+ *   m_krn_lsys_sys_umap.dst_addr	(returns physical address)
+ *   m_lsys_krn_sys_umap.nr_bytes	(size of datastructure)
  */
 
 #include "kernel/system.h"
@@ -26,12 +26,12 @@
 int do_umap_remote(struct proc * caller, message * m_ptr)
 {
 /* Map virtual address to physical, for non-kernel processes. */
-  int seg_type = m_ptr->UMAP_SEG & SEGMENT_TYPE;
-  int seg_index = m_ptr->UMAP_SEG & SEGMENT_INDEX;
-  vir_bytes offset = m_ptr->CP_SRC_ADDR;
-  int count = m_ptr->CP_NR_BYTES;
-  int endpt = (int) m_ptr->CP_SRC_ENDPT;
-  endpoint_t grantee = (endpoint_t) m_ptr->CP_DST_ENDPT;
+  int seg_type = m_ptr->m_lsys_krn_sys_umap.segment & SEGMENT_TYPE;
+  int seg_index = m_ptr->m_lsys_krn_sys_umap.segment & SEGMENT_INDEX;
+  vir_bytes offset = m_ptr->m_lsys_krn_sys_umap.src_addr;
+  int count = m_ptr->m_lsys_krn_sys_umap.nr_bytes;
+  endpoint_t endpt = m_ptr->m_lsys_krn_sys_umap.src_endpt;
+  endpoint_t grantee = m_ptr->m_lsys_krn_sys_umap.dst_endpt;
   int proc_nr, proc_nr_grantee;
   phys_bytes phys_addr = 0, lin_addr = 0;
   struct proc *targetpr;
@@ -108,7 +108,7 @@ int do_umap_remote(struct proc * caller, message * m_ptr)
 	return EFAULT;
   }
 
-  m_ptr->CP_DST_ADDR = phys_addr;
+  m_ptr->m_krn_lsys_sys_umap.dst_addr = phys_addr;
   if(phys_addr == 0) {
 	  printf("kernel: umap 0x%x done by %d / %s, pc 0x%lx, 0x%lx -> 0x%lx\n",
 		seg_type, caller->p_endpoint, caller->p_name,
diff --git a/lib/libsys/arch/i386/sys_umap_remote.c b/lib/libsys/arch/i386/sys_umap_remote.c
index 2adda8ec4..06f8d8259 100644
--- a/lib/libsys/arch/i386/sys_umap_remote.c
+++ b/lib/libsys/arch/i386/sys_umap_remote.c
@@ -22,14 +22,14 @@ phys_bytes *phys_addr;			/* placeholder for result */
      * - In all other cases, should be a valid endpoint (neither ANY nor NONE).
      */
 
-    m.CP_SRC_ENDPT = proc_ep;
-    m.CP_DST_ENDPT = grantee;
-    m.UMAP_SEG = seg;
-    m.CP_SRC_ADDR = vir_addr;
-    m.CP_NR_BYTES = bytes;
+    m.m_lsys_krn_sys_umap.src_endpt = proc_ep;
+    m.m_lsys_krn_sys_umap.dst_endpt = grantee;
+    m.m_lsys_krn_sys_umap.segment = seg;
+    m.m_lsys_krn_sys_umap.src_addr = vir_addr;
+    m.m_lsys_krn_sys_umap.nr_bytes = bytes;
 
     result = _kernel_call(SYS_UMAP_REMOTE, &m);
-    *phys_addr = m.CP_DST_ADDR;
+    *phys_addr = m.m_krn_lsys_sys_umap.dst_addr;
     return(result);
 }
 
diff --git a/lib/libsys/sys_umap.c b/lib/libsys/sys_umap.c
index e2e3ce467..c970ed0ec 100644
--- a/lib/libsys/sys_umap.c
+++ b/lib/libsys/sys_umap.c
@@ -13,13 +13,13 @@ phys_bytes *phys_addr;			/* placeholder for result */
     message m;
     int result;
 
-    m.CP_SRC_ENDPT = proc_ep;
-    m.UMAP_SEG = seg;
-    m.CP_SRC_ADDR = vir_addr;
-    m.CP_NR_BYTES = bytes;
+    m.m_lsys_krn_sys_umap.src_endpt = proc_ep;
+    m.m_lsys_krn_sys_umap.segment = seg;
+    m.m_lsys_krn_sys_umap.src_addr = vir_addr;
+    m.m_lsys_krn_sys_umap.nr_bytes = bytes;
 
     result = _kernel_call(SYS_UMAP, &m);
-    *phys_addr = m.CP_DST_ADDR;
+    *phys_addr = m.m_krn_lsys_sys_umap.dst_addr;
     return(result);
 }