diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/hrt.c b/libraries/AP_HAL_ChibiOS/hwdef/common/hrt.c
index 21f9cc002f..72418cc51d 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/hrt.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/hrt.c
@@ -41,16 +41,12 @@
   for micros64()
 */
 
-#if CH_CFG_ST_FREQUENCY != 1000000U && CH_CFG_ST_FREQUENCY != 1000U
-#error "unsupported tick frequency"
-#endif
-
 #if CH_CFG_ST_RESOLUTION == 16
 static uint32_t system_time_u32_us(void)
 {
     systime_t now = chVTGetSystemTimeX();
-#if CH_CFG_ST_FREQUENCY == 1000U
-    now *= 1000U;
+#if CH_CFG_ST_FREQUENCY != 1000000U
+    now *= 1000000U/CH_CFG_ST_FREQUENCY;
 #endif
     static systime_t last_systime;
     static uint32_t timer_base_us32;
@@ -63,8 +59,8 @@ static uint32_t system_time_u32_us(void)
 static uint32_t system_time_u32_us(void)
 {
     systime_t now = chVTGetSystemTimeX();
-#if CH_CFG_ST_FREQUENCY == 1000U
-    now *= 1000U;
+#if CH_CFG_ST_FREQUENCY != 1000000U
+    now *= 1000000U/CH_CFG_ST_FREQUENCY;
 #endif
     return now;
 }