diff --git a/kernel/system.c b/kernel/system.c
index deb2dae1b..2137559ee 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -105,6 +105,8 @@ PRIVATE int kernel_call_dispatch(struct proc * caller, message *msg)
 	  result = EBADREQUEST;			/* illegal message type */
   }
   else if (!GET_BIT(priv(caller)->s_k_call_mask, call_nr)) {
+	  printf("SYSTEM: denied request %d from %d.\n",
+			  call_nr,msg->m_source);
 	  result = ECALLDENIED;			/* illegal message type */
   } else {
 	  /* handle the system call */