diff --git a/sys/amd64/amd64/tsc.c b/sys/amd64/amd64/tsc.c
index 847c1eb..6dce88b 100644
--- a/sys/amd64/amd64/tsc.c
+++ b/sys/amd64/amd64/tsc.c
@@ -49,7 +49,7 @@ __FBSDID("$FreeBSD$");
 uint64_t	tsc_freq;
 int		tsc_is_broken;
 int		tsc_is_invariant;
-static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag;
+static eventhandler_tag tsc_pre_tag, tsc_post_tag;
 
 SYSCTL_INT(_kern_timecounter, OID_AUTO, invariant_tsc, CTLFLAG_RDTUN,
     &tsc_is_invariant, 0, "Indicates whether the TSC is P-state invariant");
@@ -67,7 +67,6 @@ static void tsc_freq_changed(void *arg, const struct cf_level *level,
 static void tsc_freq_changing(void *arg, const struct cf_level *level,
     int *status);
 static	unsigned tsc_get_timecount(struct timecounter *tc);
-static void tsc_levels_changed(void *arg, int unit);
 
 static struct timecounter tsc_timecounter = {
 	tsc_get_timecount,	/* get_timecount */
@@ -100,15 +99,16 @@ init_TSC(void)
 	 * via tsc_freq_max().  This also will be updated if someone loads
 	 * a cpufreq driver after boot that discovers a new max frequency.
 	 */
-	set_cputicker(rdtsc, tsc_freq, 1);
+	if (tsc_is_invariant)
+		set_cputicker(rdtsc, tsc_freq, 1);
+	else
+		set_cputicker(NULL, 0, 0);
 
 	/* Register to find out about changes in CPU frequency. */
 	tsc_pre_tag = EVENTHANDLER_REGISTER(cpufreq_pre_change,
 	    tsc_freq_changing, NULL, EVENTHANDLER_PRI_FIRST);
 	tsc_post_tag = EVENTHANDLER_REGISTER(cpufreq_post_change,
 	    tsc_freq_changed, NULL, EVENTHANDLER_PRI_FIRST);
-	tsc_levels_tag = EVENTHANDLER_REGISTER(cpufreq_levels_changed,
-	    tsc_levels_changed, NULL, EVENTHANDLER_PRI_ANY);
 }
 
 void
@@ -135,43 +135,6 @@ init_TSC_tc(void)
 }
 
 /*
- * When cpufreq levels change, find out about the (new) max frequency.  We
- * use this to update CPU accounting in case it got a lower estimate at boot.
- */
-static void
-tsc_levels_changed(void *arg, int unit)
-{
-	device_t cf_dev;
-	struct cf_level *levels;
-	int count, error;
-	uint64_t max_freq;
-
-	/* Only use values from the first CPU, assuming all are equal. */
-	if (unit != 0)
-		return;
-
-	/* Find the appropriate cpufreq device instance. */
-	cf_dev = devclass_get_device(devclass_find("cpufreq"), unit);
-	if (cf_dev == NULL) {
-		printf("tsc_levels_changed() called but no cpufreq device?\n");
-		return;
-	}
-
-	/* Get settings from the device and find the max frequency. */
-	count = 64;
-	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
-	if (levels == NULL)
-		return;
-	error = CPUFREQ_LEVELS(cf_dev, levels, &count);
-	if (error == 0 && count != 0) {
-		max_freq = (uint64_t)levels[0].total_set.freq * 1000000;
-		set_cputicker(rdtsc, max_freq, 1);
-	} else
-		printf("tsc_levels_changed: no max freq found\n");
-	free(levels, M_TEMP);
-}
-
-/*
  * If the TSC timecounter is in use, veto the pending change.  It may be
  * possible in the future to handle a dynamically-changing timecounter rate.
  */