diff --git a/src/api/ipc.c b/src/api/ipc.c
index ab211b5..81a9ffd 100644
--- a/src/api/ipc.c
+++ b/src/api/ipc.c
@@ -196,6 +196,20 @@ static inline int __sys_ipc(l4id_t to, l4id_t from, unsigned int ipc_type)
 	return ret;
 }
 
+void printk_sysregs(struct syscall_args *regs)
+{
+	printk("System call registers for tid: %d\n", current->tid);
+	printk("R0: %x\n", regs->r0);
+	printk("R1: %x\n", regs->r1);
+	printk("R2: %x\n", regs->r2);
+	printk("R3: %x\n", regs->r3);
+	printk("R4: %x\n", regs->r4);
+	printk("R5: %x\n", regs->r5);
+	printk("R6: %x\n", regs->r6);
+	printk("R7: %x\n", regs->r7);
+	printk("R8: %x\n", regs->r8);
+}
+
 /*
  * sys_ipc has multiple functions. In a nutshell:
  * - Copies message registers from one thread to another.
diff --git a/tasks/fs0/main.c b/tasks/fs0/main.c
index 02e90da..b3d0987 100644
--- a/tasks/fs0/main.c
+++ b/tasks/fs0/main.c
@@ -71,7 +71,7 @@ void handle_fs_requests(void)
 
 void main(void)
 {
-	printf("\n\n%s: Started.\n", __TASKNAME__);
+	printf("\n\n%s: Started with tid: %d\n", __TASKNAME__, self_tid());
 
 	initialise();
 
diff --git a/tasks/libl4/include/l4lib/arch-arm/syscalls.h b/tasks/libl4/include/l4lib/arch-arm/syscalls.h
index f118cd8..fccfce6 100644
--- a/tasks/libl4/include/l4lib/arch-arm/syscalls.h
+++ b/tasks/libl4/include/l4lib/arch-arm/syscalls.h
@@ -30,9 +30,9 @@ typedef int (*__l4_getid_t)(struct task_ids *ids);
 extern __l4_getid_t __l4_getpid;
 int l4_getid(struct task_ids *ids);
 
-typedef int (*__l4_ipc_t)(l4id_t to, l4id_t from, u32 tag);
+typedef int (*__l4_ipc_t)(l4id_t to, l4id_t from);
 extern __l4_ipc_t __l4_ipc;
-int l4_ipc(l4id_t to, l4id_t from, u32 tag);
+int l4_ipc(l4id_t to, l4id_t from);
 
 typedef int (*__l4_kread_t)(u32 rd, void *addr);
 extern __l4_kread_t __l4_kread;
diff --git a/tasks/libl4/include/l4lib/arch-arm/syslib.h b/tasks/libl4/include/l4lib/arch-arm/syslib.h
index 7825156..aa68300 100644
--- a/tasks/libl4/include/l4lib/arch-arm/syslib.h
+++ b/tasks/libl4/include/l4lib/arch-arm/syslib.h
@@ -39,7 +39,7 @@ static inline l4id_t l4_get_sender(void)
 
 static inline void l4_set_sender(l4id_t id)
 {
-	write_mr(MR_SENDER, (unsigned int)id);
+	write_mr((unsigned int)id, MR_SENDER);
 }
 
 static inline unsigned int l4_get_tag(void)
@@ -49,7 +49,7 @@ static inline unsigned int l4_get_tag(void)
 
 static inline void l4_set_tag(unsigned int tag)
 {
-	write_mr(MR_TAG, tag);
+	write_mr(tag, MR_TAG);
 }
 
 static inline l4id_t self_tid(void)
@@ -64,7 +64,8 @@ static inline int l4_send(l4id_t to, unsigned int tag)
 {
 	l4_set_tag(tag);
 	l4_set_sender(self_tid());
-	return l4_ipc(to, L4_NILTHREAD, 0);
+
+	return l4_ipc(to, L4_NILTHREAD);
 }
 
 static inline int l4_sendrecv(l4id_t to, l4id_t from, unsigned int tag)
@@ -72,12 +73,12 @@ static inline int l4_sendrecv(l4id_t to, l4id_t from, unsigned int tag)
 	BUG_ON(to == L4_NILTHREAD || from == L4_NILTHREAD);
 	l4_set_tag(tag);
 	l4_set_sender(self_tid());
-	return l4_ipc(to, from, 0);
+	return l4_ipc(to, from);
 }
 
 static inline int l4_receive(l4id_t from)
 {
-	return l4_ipc(L4_NILTHREAD, from, 0);
+	return l4_ipc(L4_NILTHREAD, from);
 }
 
 /* Servers:
diff --git a/tasks/libl4/src/arm/syscalls.S b/tasks/libl4/src/arm/syscalls.S
index d9c01b6..c4f39cb 100644
--- a/tasks/libl4/src/arm/syscalls.S
+++ b/tasks/libl4/src/arm/syscalls.S
@@ -43,12 +43,12 @@ END_PROC(l4_kread)
 
 /*
  * Inter-process communication. Loads message registers as arguments before the call,
- * and stores them as results after the call. @r0 = to, @r1 = from, @r2 = tag.
+ * and stores them as results after the call. @r0 = to, @r1 = from.
  */
 BEGIN_PROC(l4_ipc)
 	stmfd	sp!, {r4-r8,lr}		@ Save context.
 	utcb_address r12		@ Get utcb address.
-	ldmib	r12!, {r3-r8}		@ Load 5 Message registers from utcb. MR1-MR5
+	ldmia	r12!, {r3-r8}		@ Load 6 Message registers from utcb. MR1-MR5
 	ldr	r12, =__l4_ipc
 	mov	lr, pc
 	ldr	pc, [r12]
diff --git a/tasks/mm0/main.c b/tasks/mm0/main.c
index 9f6d225..8b0c60e 100644
--- a/tasks/mm0/main.c
+++ b/tasks/mm0/main.c
@@ -105,7 +105,11 @@ void handle_requests(void)
 	}
 	default:
 		printf("%s: Unrecognised ipc tag (%d) "
-		       "received. Ignoring.\n", __TASKNAME__, tag);
+		       "received from (%d). Full mr reading: "
+		       "%u, %u, %u, %u, %u, %u. Ignoring.\n",
+		       __TASKNAME__, tag, sender, read_mr(0),
+		       read_mr(1), read_mr(2), read_mr(3), read_mr(4),
+		       read_mr(5));
 	}
 }
 
diff --git a/tasks/test0/main.c b/tasks/test0/main.c
index 576110b..6ed7223 100644
--- a/tasks/test0/main.c
+++ b/tasks/test0/main.c
@@ -17,13 +17,15 @@
 void wait_pager(l4id_t partner)
 {
 	printf("%s: Syncing with pager.\n", __TASKNAME__);
+	for (int i = 0; i < 6; i++)
+		write_mr(i, i);
 	l4_send(partner, L4_IPC_TAG_WAIT);
 	printf("Pager synced with us.\n");
 }
 
 void main(void)
 {
-	printf("\n%s: Started.\n", __TASKNAME__);
+	printf("\n%s: Started with tid %d.\n", __TASKNAME__, self_tid());
 	/* Sync with pager */
 	while (1)
 		wait_pager(0);