diff --git a/include/l4/api/kip.h b/include/l4/api/kip.h
index 60c31e8..7348a34 100644
--- a/include/l4/api/kip.h
+++ b/include/l4/api/kip.h
@@ -95,4 +95,5 @@ struct kip {
 extern struct kip kip;
 #endif /* __KERNEL__ */
 
+
 #endif /* __KIP_H__ */
diff --git a/include/l4/glue/arm/utcb.h b/include/l4/glue/arm/utcb.h
index 8b0fad5..97f5285 100644
--- a/include/l4/glue/arm/utcb.h
+++ b/include/l4/glue/arm/utcb.h
@@ -8,6 +8,10 @@
 
 #define MR_TOTAL		6
 
+#define	MR_TAG		0
+#define MR_SENDER	1
+#define MR_UNUSED_START	2
+
 /* Compact utcb for now! 8-) */
 struct utcb {
 	u32 mr[MR_TOTAL];
diff --git a/src/api/ipc.c b/src/api/ipc.c
index 2fec995..aa6389e 100644
--- a/src/api/ipc.c
+++ b/src/api/ipc.c
@@ -12,6 +12,7 @@
 #include <l4/lib/bit.h>
 #include <l4/generic/kmalloc.h>
 #include INC_API(syscall.h)
+#include INC_GLUE(utcb.h)
 
 enum IPC_TYPE {
 	IPC_INVALID = 0,
@@ -22,8 +23,12 @@ enum IPC_TYPE {
 
 /*
  * Copies message registers from one ktcb stack to another. During the return
- * from system call, the registers are popped from the stack. On fast ipc path
- * they shouldn't even be pushed to the stack to avoid extra copying.
+ * from system call, the registers are popped from the stack. In the future
+ * this should be optimised so that they shouldn't even be pushed to the stack
+ *
+ * This also copies the sender into MR0 in case the receiver receives from
+ * L4_ANYTHREAD. This is done for security since the receiver cannot trust
+ * the sender info provided by the sender task.
  */
 int ipc_msg_copy(struct ktcb *to, struct ktcb *from)
 {
@@ -35,6 +40,10 @@ int ipc_msg_copy(struct ktcb *to, struct ktcb *from)
 	 */
 	memcpy(mr0_dst, mr0_src, MR_TOTAL * sizeof(unsigned int));
 
+	/* Save the sender id in case of ANYTHREAD receiver */
+	if (to->senderid == L4_ANYTHREAD)
+		mr0_dst[MR_SENDER] = from->tid;
+
 	return 0;
 }
 
@@ -241,6 +250,8 @@ int sys_ipc(struct syscall_args *regs)
 		ret = -EINVAL;
 		goto error;
 	}
+
+	/* Cannot send to self, or receive from self */
 	if (from == current->tid || to == current->tid) {
 		ret = -EINVAL;
 		goto error;
diff --git a/src/arch/arm/exception.c b/src/arch/arm/exception.c
index 31322db..01aa427 100644
--- a/src/arch/arm/exception.c
+++ b/src/arch/arm/exception.c
@@ -16,15 +16,6 @@
 #include INC_GLUE(utcb.h)
 #include INC_SUBARCH(mm.h)
 
-/*
- * NOTE: These are defined in libl4 headers for userspace. Syslib uses
- * these as conventional mr offsets to store ipc-related data commonly needed
- * for all ipc parties.
- */
-#define	MR_TAG		0
-#define MR_SENDER	1
-#define MR_UNUSED_START	2
-
 /* Send data fault ipc to the faulty task's pager */
 void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
 {
diff --git a/tasks/libl4/include/l4lib/arch-arm/syslib.h b/tasks/libl4/include/l4lib/arch-arm/syslib.h
index 4de46f5..bbfe77f 100644
--- a/tasks/libl4/include/l4lib/arch-arm/syslib.h
+++ b/tasks/libl4/include/l4lib/arch-arm/syslib.h
@@ -37,11 +37,6 @@ static inline l4id_t l4_get_sender(void)
 	return (l4id_t)read_mr(MR_SENDER);
 }
 
-static inline void l4_set_sender(l4id_t id)
-{
-	write_mr(MR_SENDER, (unsigned int)id);
-}
-
 static inline unsigned int l4_get_tag(void)
 {
 	return read_mr(MR_TAG);
@@ -63,7 +58,6 @@ static inline l4id_t self_tid(void)
 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);
 }
@@ -72,7 +66,7 @@ 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);
 }