diff --git a/repos/base-hw/src/core/spec/x86/kernel/thread.cc b/repos/base-hw/src/core/spec/x86/kernel/thread.cc
index e4ff7ca09..841ff59ef 100644
--- a/repos/base-hw/src/core/spec/x86/kernel/thread.cc
+++ b/repos/base-hw/src/core/spec/x86/kernel/thread.cc
@@ -15,16 +15,27 @@
 /* core includes */
 #include <kernel/thread.h>
 
-using namespace Kernel;
+enum Cpu_exception {
+	SUPERVISOR_CALL = 0x80,
+};
 
+using namespace Kernel;
 
 Thread::Thread(unsigned const priority, unsigned const quota,
                char const * const label)
 :
 	Thread_base(this), Cpu_job(priority, quota), _state(AWAITS_START), _pd(0),
-	_utcb_phys(0), _signal_receiver(0), _label(label)
-{ PDBG("not implemented"); }
+	_utcb_phys(0), _signal_receiver(0), _label(label) {}
 
 
-void Thread::exception(unsigned const cpu) {
-	PDBG("not implemented"); }
+void Thread::exception(unsigned const cpu)
+{
+	if (trapno == SUPERVISOR_CALL) {
+		_call();
+		return;
+	} else {
+		PWRN("unknown exception 0x%lx", trapno);
+		_stop();
+		return;
+	}
+}