diff --git a/lib/route/tc.c b/lib/route/tc.c
index 29954fd..d1308a2 100644
--- a/lib/route/tc.c
+++ b/lib/route/tc.c
@@ -578,7 +578,7 @@ int rtnl_tc_calc_txtime(int bufsize, int rate)
 	
 	tx_time_secs = (double) bufsize / (double) rate;
 
-	return tx_time_secs * 1000000.;
+	return nl_us2ticks(tx_time_secs * 1000000.);
 }
 
 /**
@@ -601,7 +601,7 @@ int rtnl_tc_calc_bufsize(int txtime, int rate)
 
 	bufsize = (double) txtime * (double) rate;
 
-	return bufsize / 1000000.;
+	return nl_ticks2us(bufsize / 1000000.);
 }
 
 /**