diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index eee9c23..5d4cd7f 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -116,6 +116,10 @@ void apply_scene(uint8_t new_scene, uint8_t light)
 
 void process_lightdata(uint8_t light, float tt)
 {
+  if (tt <= 0)
+  {
+    tt = default_transitiontime;
+  }
   if (light_state[light])
   {
     step_level[light] = (bri[light] - current_bri[light]) / tt;
diff --git a/firmware/timing_control.ino b/firmware/timing_control.ino
index 521382a..2053341 100644
--- a/firmware/timing_control.ino
+++ b/firmware/timing_control.ino
@@ -187,7 +187,7 @@ void tc_update_main()
       bri[i]            = 0;
       current_bri[i]    = 0;
       current_pwm[i]    = 0;
-      transitiontime[i] = 0;
+      transitiontime[i] = default_transitiontime;
       process_lightdata(i, transitiontime[i]);
     }