diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index c47999d3a64da1010dc146103a468ee2c2ed9be4..063247c33d7c121b2ef0a37a7e57ff18ea9d15b8 100755
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -930,11 +930,9 @@ class Instrument:
         self.the_wrt_tcb_withinitial = \
             self.tps_wrt_tcb \
             + self.clock_offsets \
-            + ForEachSC(lambda sc:
-                self.clock_freqoffsets[sc] * (t + self.tps_wrt_tcb[sc]) \
-                + self.clock_freqlindrifts[sc] * (t + self.tps_wrt_tcb[sc])**2 / 2 \
-                + self.clock_freqquaddrifts[sc] * (t + self.tps_wrt_tcb[sc])**3  / 3
-            ) \
+            + self.clock_freqoffsets * (t + self.tps_wrt_tcb) \
+            + self.clock_freqlindrifts * (t + self.tps_wrt_tcb)**2 / 2 \
+            + self.clock_freqquaddrifts * (t + self.tps_wrt_tcb)**3  / 3 \
             + self.tps_wrt_tcb * self.clock_noise_fluctuations_withinitial \
             + self.integrated_clock_noise_fluctuations_withinitial