Index: kernel/generic/include/ipc/ipc.h
===================================================================
--- kernel/generic/include/ipc/ipc.h	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/include/ipc/ipc.h	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -200,5 +200,5 @@
 
 extern void ipc_cleanup(void);
-extern void ipc_backsend_err(phone_t *, call_t *, sysarg_t);
+extern void ipc_backsend_err(phone_t *, call_t *, int);
 extern void ipc_answerbox_slam_phones(answerbox_t *, bool);
 extern void ipc_cleanup_call_list(answerbox_t *, list_t *);
Index: kernel/generic/src/ipc/ipc.c
===================================================================
--- kernel/generic/src/ipc/ipc.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/ipc/ipc.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -371,5 +371,5 @@
  *
  */
-void ipc_backsend_err(phone_t *phone, call_t *call, sysarg_t err)
+void ipc_backsend_err(phone_t *phone, call_t *call, int err)
 {
 	_ipc_call_actions_internal(phone, call, false);
Index: kernel/generic/src/ipc/sysipc.c
===================================================================
--- kernel/generic/src/ipc/sysipc.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/ipc/sysipc.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -194,5 +194,5 @@
 	spinlock_unlock(&answer->forget_lock);
 
-	if ((native_t) IPC_GET_RETVAL(answer->data) == EHANGUP) {
+	if ((int) IPC_GET_RETVAL(answer->data) == EHANGUP) {
 		phone_t *phone = answer->caller_phone;
 		mutex_lock(&phone->lock);
@@ -239,5 +239,5 @@
 static void process_answer(call_t *call)
 {
-	if (((native_t) IPC_GET_RETVAL(call->data) == EHANGUP) &&
+	if (((int) IPC_GET_RETVAL(call->data) == EHANGUP) &&
 	    (call->flags & IPC_CALL_FORWARDED))
 		IPC_SET_RETVAL(call->data, EFORWARD);
Index: kernel/generic/src/ipc/sysipc_ops.c
===================================================================
--- kernel/generic/src/ipc/sysipc_ops.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/ipc/sysipc_ops.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -81,5 +81,5 @@
 int null_request_process(call_t *call, answerbox_t *box)
 {
-	return EOK;
+	return 0;
 }
 
Index: kernel/generic/src/log/log.c
===================================================================
--- kernel/generic/src/log/log.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/log/log.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -223,5 +223,5 @@
 		int rc = chr_encode(wstr[chars], buffer, &buffer_offset, 16);
 		if (rc != EOK) {
-			return rc;
+			return EOF;
 		}
 		
Index: kernel/generic/src/mm/slab.c
===================================================================
--- kernel/generic/src/mm/slab.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/mm/slab.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -102,4 +102,5 @@
 
 #include <assert.h>
+#include <errno.h>
 #include <synch/spinlock.h>
 #include <mm/slab.h>
@@ -334,5 +335,5 @@
 	irq_spinlock_unlock(&cache->slablock, true);
 	
-	if ((cache->constructor) && (cache->constructor(obj, flags))) {
+	if ((cache->constructor) && (cache->constructor(obj, flags) != EOK)) {
 		/* Bad, bad, construction failed */
 		slab_obj_destroy(cache, obj, slab);
Index: kernel/generic/src/proc/task.c
===================================================================
--- kernel/generic/src/proc/task.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/proc/task.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -185,5 +185,5 @@
 #endif
 	
-	return 0;
+	return EOK;
 }
 
Index: kernel/generic/src/proc/thread.c
===================================================================
--- kernel/generic/src/proc/thread.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/proc/thread.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -171,5 +171,5 @@
 	thread->saved_fpu_context = slab_alloc(fpu_context_cache, kmflags);
 	if (!thread->saved_fpu_context)
-		return -1;
+		return ENOMEM;
 #endif /* CONFIG_FPU_LAZY */
 #endif /* CONFIG_FPU */
@@ -201,5 +201,5 @@
 			slab_free(fpu_context_cache, thread->saved_fpu_context);
 #endif
-		return -1;
+		return ENOMEM;
 	}
 	
@@ -210,5 +210,5 @@
 #endif
 	
-	return 0;
+	return EOK;
 }
 
@@ -1008,7 +1008,4 @@
 {
 	thread_exit();
-	
-	/* Unreachable */
-	return 0;
 }
 
Index: kernel/generic/src/security/perm.c
===================================================================
--- kernel/generic/src/security/perm.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/security/perm.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -84,8 +84,8 @@
  *
  */
-static sysarg_t perm_grant(task_id_t taskid, perm_t perms)
+static int perm_grant(task_id_t taskid, perm_t perms)
 {
 	if (!(perm_get(TASK) & PERM_PERM))
-		return (sysarg_t) EPERM;
+		return EPERM;
 	
 	irq_spinlock_lock(&tasks_lock, true);
@@ -94,5 +94,5 @@
 	if ((!task) || (!container_check(CONTAINER, task->container))) {
 		irq_spinlock_unlock(&tasks_lock, true);
-		return (sysarg_t) ENOENT;
+		return ENOENT;
 	}
 	
@@ -102,5 +102,5 @@
 	
 	irq_spinlock_unlock(&tasks_lock, true);
-	return 0;
+	return EOK;
 }
 
@@ -116,5 +116,5 @@
  *
  */
-static sysarg_t perm_revoke(task_id_t taskid, perm_t perms)
+static int perm_revoke(task_id_t taskid, perm_t perms)
 {
 	irq_spinlock_lock(&tasks_lock, true);
@@ -123,5 +123,5 @@
 	if ((!task) || (!container_check(CONTAINER, task->container))) {
 		irq_spinlock_unlock(&tasks_lock, true);
-		return (sysarg_t) ENOENT;
+		return ENOENT;
 	}
 	
@@ -136,5 +136,5 @@
 		irq_spinlock_unlock(&TASK->lock, false);
 		irq_spinlock_unlock(&tasks_lock, true);
-		return (sysarg_t) EPERM;
+		return EPERM;
 	}
 	
@@ -143,5 +143,5 @@
 	
 	irq_spinlock_unlock(&tasks_lock, true);
-	return 0;
+	return EOK;
 }
 
Index: kernel/generic/src/sysinfo/sysinfo.c
===================================================================
--- kernel/generic/src/sysinfo/sysinfo.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/sysinfo/sysinfo.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -71,5 +71,5 @@
 	item->next = NULL;
 	
-	return 0;
+	return EOK;
 }
 
Index: kernel/generic/src/udebug/udebug_ipc.c
===================================================================
--- kernel/generic/src/udebug/udebug_ipc.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/udebug/udebug_ipc.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -137,5 +137,5 @@
 
 	rc = udebug_go(t, call);
-	if (rc < 0) {
+	if (rc != EOK) {
 		IPC_SET_RETVAL(call->data, rc);
 		ipc_answer(&TASK->kb.box, call);
@@ -182,5 +182,5 @@
 	 */
 	rc = udebug_thread_read(&buffer, buf_size, &copied, &needed);
-	if (rc < 0) {
+	if (rc != EOK) {
 		IPC_SET_RETVAL(call->data, rc);
 		ipc_answer(&TASK->kb.box, call);
@@ -351,5 +351,5 @@
 
 	rc = udebug_regs_read(t, &buffer);
-	if (rc < 0) {
+	if (rc != EOK) {
 		IPC_SET_RETVAL(call->data, rc);
 		ipc_answer(&TASK->kb.box, call);
@@ -397,5 +397,5 @@
 
 	rc = udebug_mem_read(uspace_src, size, &buffer);
-	if (rc < 0) {
+	if (rc != EOK) {
 		IPC_SET_RETVAL(call->data, rc);
 		ipc_answer(&TASK->kb.box, call);
Index: kernel/generic/src/udebug/udebug_ops.c
===================================================================
--- kernel/generic/src/udebug/udebug_ops.c	(revision d0c2bebfdc87b9df8cb7c858eed6cead8e2db0b3)
+++ kernel/generic/src/udebug/udebug_ops.c	(revision 7f11dc6ba31c85d4b1daa9c4ebd4d6f99082a87c)
@@ -253,5 +253,5 @@
 	mutex_unlock(&TASK->udebug.lock);
 	
-	return 0;
+	return EOK;
 }
 
@@ -285,5 +285,5 @@
 	_thread_op_end(thread);
 	
-	return 0;
+	return EOK;
 }
 
@@ -316,5 +316,5 @@
 		/* Answer will be sent when the thread becomes stoppable. */
 		_thread_op_end(thread);
-		return 0;
+		return EOK;
 	}
 	
@@ -339,5 +339,5 @@
 	mutex_unlock(&TASK->udebug.lock);
 	
-	return 0;
+	return EOK;
 }
 
@@ -414,5 +414,5 @@
 	*needed = (copied_ids + extra_ids) * sizeof(sysarg_t);
 	
-	return 0;
+	return EOK;
 }
 
@@ -437,5 +437,5 @@
 	memcpy(*data, TASK->name, name_size);
 	
-	return 0;
+	return EOK;
 }
 
@@ -480,5 +480,5 @@
 	
 	*buffer = arg_buffer;
-	return 0;
+	return EOK;
 }
 
@@ -522,5 +522,5 @@
 	
 	*buffer = (void *) state_buf;
-	return 0;
+	return EOK;
 }
 
@@ -560,5 +560,5 @@
 	
 	*buffer = data_buffer;
-	return 0;
+	return EOK;
 }