Index: kernel/arch/amd64/include/istate.h
===================================================================
--- kernel/arch/amd64/include/istate.h	(revision c06994673347954891a57710998cf1e087a59e8b)
+++ kernel/arch/amd64/include/istate.h	(revision 5759642fc10d592323e48fdc42f5ca4046946fd0)
@@ -66,8 +66,10 @@
 } istate_t;
 
+#define RPL_USER	3
+
 /** Return true if exception happened while in userspace */
 NO_TRACE static inline int istate_from_uspace(istate_t *istate)
 {
-	return !(istate->rip & UINT64_C(0x8000000000000000));
+	return (istate->cs & RPL_USER) == RPL_USER;
 }