diff --git a/tc/tc_core.c b/tc/tc_core.c
index 58155fbf..fb898766 100644
--- a/tc/tc_core.c
+++ b/tc/tc_core.c
@@ -35,12 +35,12 @@ int tc_core_time2big(long time)
 }
 
 
-long tc_core_time2tick(long time)
+unsigned tc_core_time2tick(unsigned time)
 {
 	return time*tick_in_usec;
 }
 
-long tc_core_tick2time(long tick)
+unsigned tc_core_tick2time(unsigned tick)
 {
 	return tick/tick_in_usec;
 }
diff --git a/tc/tc_core.h b/tc/tc_core.h
index a139da6f..b2a16bc3 100644
--- a/tc/tc_core.h
+++ b/tc/tc_core.h
@@ -7,8 +7,8 @@
 #define TIME_UNITS_PER_SEC	1000000
 
 int  tc_core_time2big(long time);
-long tc_core_time2tick(long time);
-long tc_core_tick2time(long tick);
+unsigned tc_core_time2tick(unsigned time);
+unsigned tc_core_tick2time(unsigned tick);
 long tc_core_time2ktime(long time);
 long tc_core_ktime2time(long ktime);
 unsigned tc_calc_xmittime(unsigned rate, unsigned size);