diff --git a/thermopi/screen.py b/thermopi/screen.py
index 23b7dec..aaf9e3f 100644
--- a/thermopi/screen.py
+++ b/thermopi/screen.py
@@ -79,6 +79,7 @@ def main(windowed_mode):
                     running = False
             if event.type == pygame.MOUSEBUTTONDOWN:
                 get_mouse_speed = True
+                prev_mouse_pos = mouse_pos
             if event.type == pygame.MOUSEBUTTONUP:
                 get_mouse_speed = False