diff --git a/steer-pid.py b/steer-pid.py
index 4b8c592..4c376f1 100644
--- a/steer-pid.py
+++ b/steer-pid.py
@@ -101,7 +101,7 @@ for chunk in stream.iter_content(chunk_size=1024):
                     v = 0.25
 
                     p = -x
-                    d = (x - xp) / dtms * 1000
+                    d = (x - xp) * 1000 / dtms
                     i = mri * ip + x * dtms
 
                     k = wp * p + wi * i + wd * d