diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c
index 054aeeb6..d2e87e37 100644
--- a/arch/x86/kernel/apic.c
+++ b/arch/x86/kernel/apic.c
@@ -589,10 +589,10 @@ int apic_calibration(void)
 	lapic_write(APIC_ICR, 0xFFFFFFFFUL);
 	
 	/* wait 3 time slices to determine a ICR */
-	mb();
+	rmb();
 	start = rdtsc();
 	do {
-		mb();
+		rmb();
 		end = rdtsc();
 		ticks = end > start ? end - start : start - end;
 	} while(ticks*TIMER_FREQ < 3*RC_REFCLOCKMHZ*1000000UL);
diff --git a/arch/x86/kernel/processor.c b/arch/x86/kernel/processor.c
index 4802bc8e..479e589b 100644
--- a/arch/x86/kernel/processor.c
+++ b/arch/x86/kernel/processor.c
@@ -149,12 +149,12 @@ uint32_t detect_cpu_frequency(void)
 	while((ticks = get_clock_tick()) - old == 0)
 		HALT;
 
-	mb();
+	rmb();
 	start = rdtsc();
 	/* wait a second to determine the frequency */
 	while(get_clock_tick() - ticks < TIMER_FREQ)
 		HALT;
-	mb();
+	rmb();
 	end = rdtsc();
 
 	diff = end > start ? end - start : start - end;
diff --git a/arch/x86/kernel/timer.c b/arch/x86/kernel/timer.c
index 2e35a790..10ee4dbe 100644
--- a/arch/x86/kernel/timer.c
+++ b/arch/x86/kernel/timer.c
@@ -50,8 +50,8 @@ uint64_t get_clock_tick(void)
 void start_tickless(void)
 {
 	use_tickless = 1;
+	rmb();
 	last_rdtsc = rdtsc();
-	mb();
 }
 
 void end_tickless(void)
@@ -71,11 +71,11 @@ void check_ticks(void)
 	{
 		uint64_t curr_rdtsc = rdtsc();
 
-		mb();
+		rmb();
 		if (curr_rdtsc - last_rdtsc > 1000000ULL*(uint64_t)get_cpu_frequency() / (uint64_t)TIMER_FREQ) {
 			timer_ticks++;
 			last_rdtsc = curr_rdtsc;
-			mb();
+			rmb();
 		}
 	}
 }
@@ -115,6 +115,7 @@ static void timer_handler(struct state *s)
 			vga_puts("One second has passed\n");
 		}*/
 
+		kputs("A");
 		/* Dump load every minute */
 		//if (timer_ticks % (TIMER_FREQ*60) == 0)
 		//	dump_load();