diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c
--- a/sys/x86/x86/tsc.c
+++ b/sys/x86/x86/tsc.c
@@ -59,6 +59,7 @@
 uint64_t	tsc_freq;
 int		tsc_is_invariant;
 int		tsc_perf_stat;
+static int	tsc_early_calib_exact;
 
 static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag;
 
@@ -133,6 +134,7 @@
 			tsc_freq = regs[0] | ((uint64_t)regs[1] << 32);
 	}
 	tsc_is_invariant = 1;
+	tsc_early_calib_exact = 1;
 }
 
 /*
@@ -709,6 +711,8 @@
 
 	if (tsc_disabled)
 		return;
+	if (tsc_early_calib_exact)
+		goto calibrated;
 
 	tc = atomic_load_ptr(&timecounter);
 
@@ -739,6 +743,7 @@
 	freq_khz = tc->tc_frequency * (tsc_end - tsc_start) / (t_end - t_start);
 
 	tsc_update_freq(freq_khz);
+calibrated:
 	tc_init(&tsc_timecounter);
 	set_cputicker(rdtsc, tsc_freq, !tsc_is_invariant);
 }