diff --git a/auto_rx/autorx/utils.py b/auto_rx/autorx/utils.py
index 6773a1e..bfd38ed 100644
--- a/auto_rx/autorx/utils.py
+++ b/auto_rx/autorx/utils.py
@@ -28,7 +28,7 @@ except ImportError:
 
 
 # List of binaries we check for on startup
-REQUIRED_RS_UTILS = ['dft_detect', 'dfm09ecc', 'm10', 'imet1rs_dft', 'rs41mod', 'rs92mod']
+REQUIRED_RS_UTILS = ['dft_detect', 'dfm09ecc', 'm10', 'imet1rs_dft', 'rs41mod', 'rs92mod', 'fsk_demod']
 
 def check_rs_utils():
     """ Check the required RS decoder binaries exist
@@ -36,7 +36,7 @@ def check_rs_utils():
     """
     for _file in REQUIRED_RS_UTILS:
         if not os.path.isfile(_file):
-            logging.critical("RS binary %s does not exist - did you run build.sh?" % _file)
+            logging.critical("Binary %s does not exist - did you run build.sh?" % _file)
             return False
 
     return True
diff --git a/auto_rx/build.sh b/auto_rx/build.sh
index c7f57fb..10cbfa8 100755
--- a/auto_rx/build.sh
+++ b/auto_rx/build.sh
@@ -41,8 +41,8 @@ echo "Building fsk-demod utils from codec2"
 cd ../utils/
 # This produces a static build of fsk_demod
 gcc fsk_demod.c fsk.c modem_stats.c kiss_fftr.c kiss_fft.c -lm -o fsk_demod
-# Build tsrc
-gcc tsrc.c -o tsrc -lm -lsamplerate
+# Build tsrc - this is only required for the test/test_demod.py script, so is not included in the standard build.
+#gcc tsrc.c -o tsrc -lm -lsamplerate
 # If running under OSX, you may need to uncomment the following line to be able to find libsamplerate.
 #gcc tsrc.c -o tsrc -lm -lsamplerate -I/opt/local/include -L/opt/local/lib
 
@@ -56,7 +56,6 @@ cp ../demod/rs41ecc .
 cp ../demod/dfm09ecc .
 cp ../m10/m10 .
 cp ../utils/fsk_demod .
-cp ../utils/tsrc .
 cp ../imet/imet1rs_dft .
 
 cp ../demod/mod/rs41mod .