diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index 1893ecfa39fde3009c22be8633acdd55d31c80ec..1f682eb551c55ea89e01ef5a04f191f170e9c059 100644
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -587,7 +587,8 @@ class Instrument:
         logger.debug("Propagating local carrier fluctuations to test-mass interferometer")
         self.local_tm_carrier_fluctuations = \
             self.local_carrier_fluctuations \
-            + self.central_freq * (self.testmass_noises + self.glitch_tms / c)
+            + (self.testmass_noises + self.glitch_tms / c) \
+            * (self.central_freq + self.local_tm_carrier_offsets)
 
         logger.debug("Propagating local upper sideband offsets to test-mass interferometer")
         self.local_tm_usb_offsets = self.local_usb_offsets
@@ -595,7 +596,8 @@ class Instrument:
         logger.debug("Propagating local upper sideband fluctuations to test-mass interferometer")
         self.local_tm_usb_fluctuations = \
             self.local_usb_fluctuations \
-            + self.central_freq * (self.testmass_noises + self.glitch_tms / c)
+            + (self.testmass_noises + self.glitch_tms / c) \
+            * (self.central_freq + self.local_tm_usb_offsets)
 
         ## Test-mass interferometer adjacent beams