diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index c52160229c1298670e276c2fee45296ff498dbd9..afaaa50c5edb9af7a4af5a61dfa0c4063d9fa05c 100644
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -594,6 +594,15 @@ class Instrument:
 
         ## TDIR tone
 
+        logger.debug("Computing local timer deviations")
+        self.local_timer_deviations = \
+            self.clock_offsets + ForEachSC(lambda sc:
+                numpy.cumsum(numpy.broadcast_to(
+                    self.clock_noise_offsets[sc] + self.clock_noise_fluctuations[sc],
+                    self.physics_size)
+                * self.physics_dt)
+            )
+
         self.tdir_tones = ForEachMOSA(lambda mosa:
             0 if self.tdir_tone_amplitudes[mosa] == 0 \
             else self.tdir_tone_amplitudes[mosa] * numpy.sin(
@@ -608,15 +617,6 @@ class Instrument:
         logger.info("Simulating local beams")
         self.simulate_locking()
 
-        logger.debug("Computing local timer deviations")
-        self.local_timer_deviations = \
-            self.clock_offsets + ForEachSC(lambda sc:
-                numpy.cumsum(numpy.broadcast_to(
-                    self.clock_noise_offsets[sc] + self.clock_noise_fluctuations[sc],
-                    self.physics_size)
-                * self.physics_dt)
-            )
-
         ## Propagation to distant MOSA
 
         logger.info("Propagating local beams to distant MOSAs")