diff --git a/lib/system/freertos/sleep.h b/lib/system/freertos/sleep.h
index f114a4e..60a58a1 100644
--- a/lib/system/freertos/sleep.h
+++ b/lib/system/freertos/sleep.h
@@ -25,7 +25,7 @@ extern "C" {
 
 static inline int __metal_sleep_usec(unsigned int usec)
 {
-	const TickType_t xDelay = ((usec/1000) / portTICK_PERIOD_MS);
+	const TickType_t xDelay = pdMS_TO_TICKS(usec/1000);
 
 	vTaskDelay(xDelay ? xDelay : 1);
 	return 0;