diff --git a/include/minix/com.h b/include/minix/com.h
index e0985618f..8534feb7d 100644
--- a/include/minix/com.h
+++ b/include/minix/com.h
@@ -283,7 +283,8 @@
 #  define SYS_SETTIME    (KERNEL_CALL + 40)	/* sys_settime() */
 
 #  define SYS_VMCTL      (KERNEL_CALL + 43)	/* sys_vmctl() */
-#  define SYS_SYSCTL     (KERNEL_CALL + 44)	/* sys_sysctl() */
+
+#  define SYS_DIAGCTL    (KERNEL_CALL + 44)	/* sys_diagctl() */
 
 #  define SYS_VTIMER     (KERNEL_CALL + 45)	/* sys_vtimer() */
 #  define SYS_RUNCTL     (KERNEL_CALL + 46)	/* sys_runctl() */
@@ -309,7 +310,7 @@
 #define SYS_BASIC_CALLS \
     SYS_EXIT, SYS_SAFECOPYFROM, SYS_SAFECOPYTO, SYS_VSAFECOPY, SYS_GETINFO, \
     SYS_TIMES, SYS_SETALARM, SYS_SETGRANT, \
-    SYS_PROFBUF, SYS_SYSCTL, SYS_STATECTL, SYS_SAFEMEMSET
+    SYS_PROFBUF, SYS_DIAGCTL, SYS_STATECTL, SYS_SAFEMEMSET
 
 /* Field names for SYS_MEMSET. */
 #define MEM_PTR		m2_p1	/* base */
@@ -582,12 +583,12 @@
 #define VMCTL_CLEARMAPCACHE	32
 #define VMCTL_BOOTINHIBIT_CLEAR	33
 
-/* Codes and field names for SYS_SYSCTL. */
-#define SYSCTL_CODE		m1_i1	/* SYSCTL_CODE_* below */
-#define SYSCTL_ARG1		m1_p1
-#define SYSCTL_ARG2		m1_i2
-#define SYSCTL_CODE_DIAG	1	/* Print diagnostics. */
-#define SYSCTL_CODE_STACKTRACE	2	/* Print process stack. */
+/* Codes and field names for SYS_DIAGCTL. */
+#define DIAGCTL_CODE		m1_i1	/* DIAGCTL_CODE_* below */
+#define DIAGCTL_ARG1		m1_p1
+#define DIAGCTL_ARG2		m1_i2
+#define DIAGCTL_CODE_DIAG	1	/* Print diagnostics. */
+#define DIAGCTL_CODE_STACKTRACE	2	/* Print process stack. */
 #define DIAG_BUFSIZE	(80*25)
 
 /* Field names for SYS_VTIMER. */
diff --git a/include/minix/syslib.h b/include/minix/syslib.h
index 3d1d1084b..dad156080 100644
--- a/include/minix/syslib.h
+++ b/include/minix/syslib.h
@@ -69,8 +69,8 @@ int sys_vmctl_enable_paging(void * data);
 int sys_readbios(phys_bytes address, void *buf, size_t size);
 int sys_settime(int now, clockid_t clk_id, time_t sec, long nsec);
 int sys_stime(time_t boottime);
-int sys_sysctl(int ctl, char *arg1, int arg2);
-int sys_sysctl_stacktrace(endpoint_t who);
+int sys_diagctl(int ctl, char *arg1, int arg2);
+int sys_diagctl_stacktrace(endpoint_t who);
 int sys_vmctl_get_mapping(int index, phys_bytes *addr, phys_bytes *len,
 	int *flags);
 int sys_vmctl_reply_mapping(int index, vir_bytes addr);
diff --git a/kernel/proto.h b/kernel/proto.h
index 6ebe443b4..ac2b55625 100644
--- a/kernel/proto.h
+++ b/kernel/proto.h
@@ -137,8 +137,8 @@ void hook_ipc_clear(struct proc *proc);
 int verify_grant(endpoint_t, endpoint_t, cp_grant_id_t, vir_bytes, int,
 	vir_bytes, vir_bytes *, endpoint_t *);
 
-/* system/do_sysctl.c */
-int do_sysctl(struct proc * caller, message *m);
+/* system/do_diagctl.c */
+int do_diagctl(struct proc * caller, message *m);
 
 #if SPROFILE
 /* profile.c */
diff --git a/kernel/system.c b/kernel/system.c
index 3e1eff6ed..084d47760 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -241,7 +241,7 @@ void system_init(void)
   /* System control. */
   map(SYS_ABORT, do_abort);		/* abort MINIX */
   map(SYS_GETINFO, do_getinfo); 	/* request system information */ 
-  map(SYS_SYSCTL, do_sysctl); 		/* misc system manipulation */ 
+  map(SYS_DIAGCTL, do_diagctl);		/* diagnostics-related functionality */
 
   /* Profiling. */
   map(SYS_SPROF, do_sprofile);         /* start/stop statistical profiling */
diff --git a/kernel/system/Makefile.inc b/kernel/system/Makefile.inc
index e90b47640..431bbe584 100644
--- a/kernel/system/Makefile.inc
+++ b/kernel/system/Makefile.inc
@@ -25,7 +25,7 @@ SRCS+= 	\
 	do_privctl.c \
 	do_safecopy.c \
 	do_safememset.c \
-	do_sysctl.c \
+	do_diagctl.c \
 	do_getksig.c \
 	do_endksig.c \
 	do_kill.c \
diff --git a/kernel/system/do_sysctl.c b/kernel/system/do_diagctl.c
similarity index 55%
rename from kernel/system/do_sysctl.c
rename to kernel/system/do_diagctl.c
index 5bc6b100a..a75051b9d 100644
--- a/kernel/system/do_sysctl.c
+++ b/kernel/system/do_diagctl.c
@@ -1,35 +1,35 @@
 /* The kernel call implemented in this file:
- *   m_type:	SYS_SYSCTL
+ *   m_type:	SYS_DIAGCTL
  *
  * The parameters for this kernel call are:
- *  	SYSCTL_CODE	request
- * and then request-specific arguments in SYSCTL_ARG1 and SYSCTL_ARG2.
+ *  	DIAGCTL_CODE	request
+ * and then request-specific arguments in DIAGCTL_ARG1 and DIAGCTL_ARG2.
  */
 
 #include "kernel/system.h"
 
 
 /*===========================================================================*
- *			        do_sysctl				     *
+ *			        do_diagctl				     *
  *===========================================================================*/
-int do_sysctl(struct proc * caller, message * m_ptr)
+int do_diagctl(struct proc * caller, message * m_ptr)
 {
   vir_bytes len, buf;
   static char mybuf[DIAG_BUFSIZE];
   int s, i, proc_nr;
 
-  switch (m_ptr->SYSCTL_CODE) {
-    case SYSCTL_CODE_DIAG:
-        buf = (vir_bytes) m_ptr->SYSCTL_ARG1;
-        len = (vir_bytes) m_ptr->SYSCTL_ARG2;
+  switch (m_ptr->DIAGCTL_CODE) {
+    case DIAGCTL_CODE_DIAG:
+        buf = (vir_bytes) m_ptr->DIAGCTL_ARG1;
+        len = (vir_bytes) m_ptr->DIAGCTL_ARG2;
 	if(len < 1 || len > DIAG_BUFSIZE) {
-		printf("do_sysctl: diag for %d: len %d out of range\n",
+		printf("do_diagctl: diag for %d: len %d out of range\n",
 			caller->p_endpoint, len);
 		return EINVAL;
 	}
 	if((s=data_copy_vmcheck(caller, caller->p_endpoint, buf, KERNEL,
 					(vir_bytes) mybuf, len)) != OK) {
-		printf("do_sysctl: diag for %d: len %d: copy failed: %d\n",
+		printf("do_diagctl: diag for %d: len %d: copy failed: %d\n",
 			caller->p_endpoint, len, s);
 		return s;
 	}
@@ -37,13 +37,13 @@ int do_sysctl(struct proc * caller, message * m_ptr)
 		kputc(mybuf[i]);
 	kputc(END_OF_KMESS);
 	return OK;
-    case SYSCTL_CODE_STACKTRACE:
-	if(!isokendpt(m_ptr->SYSCTL_ARG2, &proc_nr))
+    case DIAGCTL_CODE_STACKTRACE:
+	if(!isokendpt(m_ptr->DIAGCTL_ARG2, &proc_nr))
 		return EINVAL;
 	proc_stacktrace(proc_addr(proc_nr));
 	return OK;
     default:
-	printf("do_sysctl: invalid request %d\n", m_ptr->SYSCTL_CODE);
+	printf("do_diagctl: invalid request %d\n", m_ptr->DIAGCTL_CODE);
         return(EINVAL);
   }
 }
diff --git a/lib/libsys/Makefile b/lib/libsys/Makefile
index 5d5759730..ba6d96018 100644
--- a/lib/libsys/Makefile
+++ b/lib/libsys/Makefile
@@ -38,6 +38,7 @@ SRCS+=  \
 	sys_abort.c \
 	sys_clear.c \
 	sys_cprof.c \
+	sys_diagctl.c \
 	sys_endsig.c \
 	sys_exec.c \
 	sys_exit.c \
@@ -66,7 +67,6 @@ SRCS+=  \
 	sys_sprof.c \
 	sys_statectl.c \
 	sys_stime.c \
-	sys_sysctl.c \
 	sys_times.c \
 	sys_trace.c \
 	sys_umap.c \
diff --git a/lib/libsys/kputc.c b/lib/libsys/kputc.c
index 9e7301272..5e3fbbf40 100644
--- a/lib/libsys/kputc.c
+++ b/lib/libsys/kputc.c
@@ -20,7 +20,7 @@ void kputc(int c)
   static int buf_count;		/* # characters in the buffer */
 
   if ((c == 0 && buf_count > 0) || buf_count == sizeof(print_buf)) {
-	sys_sysctl(SYSCTL_CODE_DIAG, print_buf, buf_count);
+	sys_diagctl(DIAGCTL_CODE_DIAG, print_buf, buf_count);
 	buf_count = 0;
   }
   if (c != 0) { 
diff --git a/lib/libsys/sys_diagctl.c b/lib/libsys/sys_diagctl.c
new file mode 100644
index 000000000..a74777c49
--- /dev/null
+++ b/lib/libsys/sys_diagctl.c
@@ -0,0 +1,19 @@
+
+#include "syslib.h"
+
+int sys_diagctl(int code, char *arg1, int arg2)
+{
+  message m;
+
+  m.DIAGCTL_CODE = code;
+  m.DIAGCTL_ARG1 = arg1;
+  m.DIAGCTL_ARG2 = arg2;
+
+  return(_kernel_call(SYS_DIAGCTL, &m));
+}
+
+int sys_diagctl_stacktrace(endpoint_t ep)
+{
+  return sys_diagctl(DIAGCTL_CODE_STACKTRACE, NULL, ep);
+}
+
diff --git a/lib/libsys/sys_sysctl.c b/lib/libsys/sys_sysctl.c
deleted file mode 100644
index 443a9cc97..000000000
--- a/lib/libsys/sys_sysctl.c
+++ /dev/null
@@ -1,20 +0,0 @@
-
-#include "syslib.h"
-
-int sys_sysctl(int code, char *arg1, int arg2)
-{
-  message m;
-
-  m.SYSCTL_CODE = code;
-  m.SYSCTL_ARG1 = arg1;
-  m.SYSCTL_ARG2 = arg2;
-
-  return(_kernel_call(SYS_SYSCTL, &m));
-
-}
-
-int sys_sysctl_stacktrace(endpoint_t ep)
-{
-  return sys_sysctl(SYSCTL_CODE_STACKTRACE, NULL, ep);
-}
-
diff --git a/servers/is/dmp_kernel.c b/servers/is/dmp_kernel.c
index 6c6a318b2..159927821 100644
--- a/servers/is/dmp_kernel.c
+++ b/servers/is/dmp_kernel.c
@@ -370,7 +370,7 @@ void procstack_dmp()
   PROCLOOP(rp, oldrp)
 	PRINTRTS(rp);
 	printf("\n"); pagelines++;
-	sys_sysctl_stacktrace(rp->p_endpoint);
+	sys_diagctl_stacktrace(rp->p_endpoint);
   }
 }
 
diff --git a/servers/pm/misc.c b/servers/pm/misc.c
index 40291a53c..579024f6b 100644
--- a/servers/pm/misc.c
+++ b/servers/pm/misc.c
@@ -142,7 +142,7 @@ int do_getsysinfo()
   {
 	printf("PM: unauthorized call of do_getsysinfo by proc %d '%s'\n",
 		mp->mp_endpoint, mp->mp_name);
-	sys_sysctl_stacktrace(mp->mp_endpoint);
+	sys_diagctl_stacktrace(mp->mp_endpoint);
 	return EPERM;
   }
 
@@ -190,7 +190,7 @@ int do_getprocnr()
 
 	printf("PM: unauthorized call of do_getprocnr by proc %d\n",
 		mp->mp_endpoint);
-	sys_sysctl_stacktrace(mp->mp_endpoint);
+	sys_diagctl_stacktrace(mp->mp_endpoint);
 	return EPERM;
   }
 
@@ -267,7 +267,7 @@ int do_getepinfo_o()
   if (mp->mp_effuid != 0) {
 	printf("PM: unauthorized call of do_getepinfo_o by proc %d\n",
 		mp->mp_endpoint);
-	sys_sysctl_stacktrace(mp->mp_endpoint);
+	sys_diagctl_stacktrace(mp->mp_endpoint);
 	return EPERM;
   }
 
diff --git a/servers/pm/signal.c b/servers/pm/signal.c
index 43122caab..fd35304c7 100644
--- a/servers/pm/signal.c
+++ b/servers/pm/signal.c
@@ -380,7 +380,7 @@ int ksig;			/* non-zero means signal comes from kernel  */
 
   	/* Print stacktrace if necessary. */
   	if(SIGS_IS_STACKTRACE(signo)) {
- 		sys_sysctl_stacktrace(rmp->mp_endpoint);
+		sys_diagctl_stacktrace(rmp->mp_endpoint);
   	}
 
   	if(!SIGS_IS_TERMINATION(signo)) {
@@ -475,7 +475,7 @@ int signo;			/* signal that caused termination */
 	if(!(rmp->mp_flags & PRIV_PROC)) {
 		printf("PM: coredump signal %d for %d / %s\n", signo,
 			rmp->mp_pid, rmp->mp_name);
-		sys_sysctl_stacktrace(rmp->mp_endpoint);
+		sys_diagctl_stacktrace(rmp->mp_endpoint);
 	}
 	exit_proc(rmp, 0, TRUE /*dump_core*/);
   }
diff --git a/servers/rs/main.c b/servers/rs/main.c
index dc1caf797..0201fe1b0 100644
--- a/servers/rs/main.c
+++ b/servers/rs/main.c
@@ -540,7 +540,7 @@ static int sef_cb_signal_manager(endpoint_t target, int signo)
 
   /* Print stacktrace if necessary. */
   if(SIGS_IS_STACKTRACE(signo)) {
-       sys_sysctl_stacktrace(target);
+       sys_diagctl_stacktrace(target);
   }
 
   /* In case of termination signal handle the event. */
diff --git a/servers/vfs/pipe.c b/servers/vfs/pipe.c
index e21536e06..135891e3b 100644
--- a/servers/vfs/pipe.c
+++ b/servers/vfs/pipe.c
@@ -567,7 +567,7 @@ void unpause(void)
 			panic("file descriptor out-of-range");
 		f = fp->fp_filp[fild];
 		if(!f) {
-			sys_sysctl_stacktrace(fp->fp_endpoint);
+			sys_diagctl_stacktrace(fp->fp_endpoint);
 			panic("process %d blocked on empty fd %d",
 				fp->fp_endpoint, fild);
 		}
diff --git a/servers/vm/mem_file.c b/servers/vm/mem_file.c
index 023e0f968..2588cdbea 100644
--- a/servers/vm/mem_file.c
+++ b/servers/vm/mem_file.c
@@ -125,7 +125,7 @@ static int mappedfile_pagefault(struct vmproc *vmp, struct vir_region *region,
 
 		if(!cb) {
 			printf("VM: mem_file: no callback, returning EFAULT\n");
-			sys_sysctl_stacktrace(vmp->vm_endpoint);
+			sys_diagctl_stacktrace(vmp->vm_endpoint);
 			return EFAULT;
 		}
 
diff --git a/servers/vm/mmap.c b/servers/vm/mmap.c
index d05c37d39..8985fcdcd 100644
--- a/servers/vm/mmap.c
+++ b/servers/vm/mmap.c
@@ -182,7 +182,7 @@ static void mmap_file_cont(struct vmproc *vmp, message *replymsg, void *cbarg,
 	if(replymsg->VMV_RESULT != OK) {
 #if 0   /* Noisy diagnostic for mmap() by ld.so */
 		printf("VM: VFS reply failed (%d)\n", replymsg->VMV_RESULT);
-		sys_sysctl_stacktrace(vmp->vm_endpoint);
+		sys_diagctl_stacktrace(vmp->vm_endpoint);
 #endif
 		result = origmsg->VMV_RESULT;
 	} else {
@@ -532,7 +532,7 @@ int do_munmap(message *m)
 	        if(!(vr = map_lookup(vmp, addr, NULL))) {
 			printf("VM: unmap: address 0x%lx not found in %d\n",
 	                       addr, target);
-			sys_sysctl_stacktrace(target);
+			sys_diagctl_stacktrace(target);
 	                return EFAULT;
 		}
 		len = vr->length;
diff --git a/servers/vm/pagefaults.c b/servers/vm/pagefaults.c
index 6ae166a68..1cba5e2e9 100644
--- a/servers/vm/pagefaults.c
+++ b/servers/vm/pagefaults.c
@@ -87,7 +87,7 @@ static void handle_pagefault(endpoint_t ep, vir_bytes addr, u32_t err, int retry
 			assert(PFERR_NOPAGE(err));
 			printf("VM: pagefault: SIGSEGV %d bad addr 0x%lx; %s\n",
 					ep, addr, pf_errstr(err));
-			sys_sysctl_stacktrace(ep);
+			sys_diagctl_stacktrace(ep);
 		}
 		if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
 			panic("sys_kill failed: %d", s);