diff --git a/kernel/arch/i386/arch_system.c b/kernel/arch/i386/arch_system.c
index 376586cd6..15ffa5cd5 100644
--- a/kernel/arch/i386/arch_system.c
+++ b/kernel/arch/i386/arch_system.c
@@ -491,8 +491,9 @@ void arch_do_syscall(struct proc *proc)
   /* do_ipc assumes that it's running because of the current process */
   assert(proc == get_cpulocal_var(proc_ptr));
   /* Make the system call, for real this time. */
+  assert(proc->p_misc_flags & MF_SC_DEFER);
   proc->p_reg.retreg =
-	  do_ipc(proc->p_reg.cx, proc->p_reg.retreg, proc->p_reg.bx);
+	  do_ipc(proc->p_defer.r1, proc->p_defer.r2, proc->p_defer.r3);
 }
 
 struct proc * arch_finish_switch_to_user(void)
diff --git a/kernel/proc.c b/kernel/proc.c
index 0518551e1..3bdabd25f 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -546,7 +546,11 @@ int do_ipc(reg_t r1, reg_t r2, reg_t r3)
 		 * input message. Postpone the entire system call.
 		 */
 		caller_ptr->p_misc_flags &= ~MF_SC_TRACE;
+		assert(!(caller_ptr->p_misc_flags & MF_SC_DEFER));
 		caller_ptr->p_misc_flags |= MF_SC_DEFER;
+		caller_ptr->p_defer.r1 = r1;
+		caller_ptr->p_defer.r2 = r2;
+		caller_ptr->p_defer.r3 = r3;
 
 		/* Signal the "enter system call" event. Block the process. */
 		cause_sig(proc_nr(caller_ptr), SIGTRAP);
diff --git a/kernel/proc.h b/kernel/proc.h
index 0d2d9148e..f645d3ea5 100644
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -121,6 +121,11 @@ struct proc {
   int p_found;	/* consistency checking variables */
   int p_magic;		/* check validity of proc pointers */
 
+  /* if MF_SC_DEFER is set, this struct is valid and contains the
+   * do_ipc() arguments that are still to be executed
+   */
+  struct { reg_t r1, r2, r3; } p_defer;
+
 #if DEBUG_TRACE
   int p_schedules;
 #endif