diff --git a/include/minix/callnr.h b/include/minix/callnr.h
index 1f674f673..8bcea61a1 100644
--- a/include/minix/callnr.h
+++ b/include/minix/callnr.h
@@ -76,11 +76,6 @@
 #define PM_SYSUNAME_LEN		m1_i3	/* char * */
 #define PM_SYSUNAME_VALUE	m1_p1	/* size_t */
 
-/* Field names for the getitimer(2)/setitimer(2) calls. */
-#define PM_ITIMER_WHICH		m1_i1	/* int */
-#define PM_ITIMER_VALUE		m1_p1	/* const struct itimerval * */
-#define PM_ITIMER_OVALUE	m1_p2	/* struct itimerval * */
-
 /* Field names for the execve(2) call. */
 #define PM_EXEC_NAME		m1_p1	/* const char * */
 #define PM_EXEC_NAMELEN		m1_i1	/* size_t */
diff --git a/include/minix/ipc.h b/include/minix/ipc.h
index cff4bfa2d..532b34408 100644
--- a/include/minix/ipc.h
+++ b/include/minix/ipc.h
@@ -145,6 +145,15 @@ typedef struct {
 } mess_sigcalls;
 _ASSERT_MSG_SIZE(mess_sigcalls);
 
+typedef struct {
+	int which;
+	vir_bytes value;	/* const struct itimerval * */
+	vir_bytes ovalue;	/* struct itimerval * */
+
+	uint8_t padding[44];
+} mess_lc_pm_itimer;
+_ASSERT_MSG_SIZE(mess_lc_pm_itimer);
+
 typedef struct {
 	time_t sec;
 
@@ -922,6 +931,7 @@ typedef struct {
 		mess_fs_vfs_readsuper	m_fs_vfs_readsuper;
 		mess_fs_vfs_readwrite	m_fs_vfs_readwrite;
 
+		mess_lc_pm_itimer	m_lc_pm_itimer;
 		mess_lc_pm_time		m_lc_pm_time;
 		mess_lc_pm_waitpid	m_lc_pm_waitpid;
 
diff --git a/lib/libc/sys-minix/getitimer.c b/lib/libc/sys-minix/getitimer.c
index 5e06e1953..cb4ac563b 100644
--- a/lib/libc/sys-minix/getitimer.c
+++ b/lib/libc/sys-minix/getitimer.c
@@ -14,9 +14,9 @@ int getitimer(int which, struct itimerval *value)
   message m;
 
   memset(&m, 0, sizeof(m));
-  m.PM_ITIMER_WHICH = which;
-  m.PM_ITIMER_VALUE = NULL;		/* only retrieve the timer */
-  m.PM_ITIMER_OVALUE = (char *) value;
+  m.m_lc_pm_itimer.which = which;
+  m.m_lc_pm_itimer.value = 0;		/* only retrieve the timer */
+  m.m_lc_pm_itimer.ovalue = (vir_bytes)value;
 
   return _syscall(PM_PROC_NR, PM_ITIMER, &m);
 }
diff --git a/lib/libc/sys-minix/setitimer.c b/lib/libc/sys-minix/setitimer.c
index 882b68657..3157793f7 100644
--- a/lib/libc/sys-minix/setitimer.c
+++ b/lib/libc/sys-minix/setitimer.c
@@ -23,9 +23,9 @@ int setitimer(int which, const struct itimerval *__restrict value,
   }
 
   memset(&m, 0, sizeof(m));
-  m.PM_ITIMER_WHICH = which;
-  m.PM_ITIMER_VALUE = (char *) __UNCONST(value);
-  m.PM_ITIMER_OVALUE = (char *) ovalue;
+  m.m_lc_pm_itimer.which = which;
+  m.m_lc_pm_itimer.value = (vir_bytes)value;
+  m.m_lc_pm_itimer.ovalue = (vir_bytes)ovalue;
 
   return _syscall(PM_PROC_NR, PM_ITIMER, &m);
 }
diff --git a/servers/pm/alarm.c b/servers/pm/alarm.c
index 93f1e93e7..d496e9db2 100644
--- a/servers/pm/alarm.c
+++ b/servers/pm/alarm.c
@@ -95,15 +95,15 @@ int do_itimer()
   int r, which;
 
   /* Make sure 'which' is one of the defined timers. */
-  which = m_in.PM_ITIMER_WHICH;
+  which = m_in.m_lc_pm_itimer.which;
   if (which < 0 || which >= NR_ITIMERS) return(EINVAL);
 
   /* Determine whether to set and/or return the given timer value, based on
    * which of the value and ovalue parameters are nonzero. At least one of
    * them must be nonzero.
    */
-  setval = (m_in.PM_ITIMER_VALUE != NULL);
-  getval = (m_in.PM_ITIMER_OVALUE != NULL);
+  setval = (m_in.m_lc_pm_itimer.value != 0);
+  getval = (m_in.m_lc_pm_itimer.ovalue != 0);
 
   if (!setval && !getval) return(EINVAL);
 
@@ -111,8 +111,8 @@ int do_itimer()
    * Also, make sure its fields have sane values.
    */
   if (setval) {
-	r = sys_datacopy(who_e, (vir_bytes) m_in.PM_ITIMER_VALUE,
-		PM_PROC_NR, (vir_bytes) &value, (phys_bytes) sizeof(value));
+	r = sys_datacopy(who_e, m_in.m_lc_pm_itimer.value,
+		PM_PROC_NR, (vir_bytes)&value, (phys_bytes)sizeof(value));
   	if (r != OK) return(r);
 
   	if (!is_sane_timeval(&value.it_value) ||
@@ -143,9 +143,9 @@ int do_itimer()
 
   /* If requested, copy the old interval timer to user space. */
   if (r == OK && getval) {
-	r = sys_datacopy(PM_PROC_NR, (vir_bytes) &ovalue,
-		who_e, (vir_bytes) m_in.PM_ITIMER_OVALUE,
-		(phys_bytes) sizeof(ovalue));
+	r = sys_datacopy(PM_PROC_NR, (vir_bytes)&ovalue,
+		who_e, m_in.m_lc_pm_itimer.ovalue,
+		(phys_bytes)sizeof(ovalue));
   }
 
   return(r);