diff --git a/test-data/ahrs/ahrs_replay.go b/test-data/ahrs/ahrs_replay.go
index 55cf7d41..a42f9edc 100644
--- a/test-data/ahrs/ahrs_replay.go
+++ b/test-data/ahrs/ahrs_replay.go
@@ -342,8 +342,8 @@ func heartBeatSender() {
 
 func main() {
 	crcInit()
-	if len(os.Args) < 4 {
-		fmt.Printf("%s <start second> <ahrs file> <gps file>\n", os.Args[0])
+	if len(os.Args) < 5 {
+		fmt.Printf("%s <start second> <ahrs file> <gps file> <replay speed>\n", os.Args[0])
 		return
 	}
 	startsec, err := strconv.Atoi(os.Args[1])
@@ -352,6 +352,12 @@ func main() {
 		return
 	}
 
+	replayspeed, err := strconv.Atoi(os.Args[4])
+	if err != nil {
+		fmt.Printf("invalid: %s\n", os.Args[4])
+		return
+	}
+
 	startnsec := int64(startsec) * 1000000000
 
 	ahrsfp, ahrsIdx, err := seekTimestampInAHRS(os.Args[2], startnsec, 1000000000) // Find the index with 1.00s tolerance.
@@ -414,9 +420,9 @@ func main() {
 		fmt.Printf("%f %f\n", pitch, roll)
 		s := fmt.Sprintf("XATTStratux,%f,%f,%f", gps.Course, pitch, roll)
 		outConn.Write([]byte(s))
-		time.Sleep(time.Duration(ahrs.Timestamp - lastTs))
+		time.Sleep(time.Duration((ahrs.Timestamp - lastTs)/int64(replayspeed)))
 		lastTs = ahrs.Timestamp
 
 		// Now we're working with synced samples.
 	}
-}
\ No newline at end of file
+}