diff --git a/pyfstat/core.py b/pyfstat/core.py
index 1016d0c06178203ac27fc537d850a4ee086e8c09..407a2edd86136a7b46be0b4615681c960345e456 100755
--- a/pyfstat/core.py
+++ b/pyfstat/core.py
@@ -1094,8 +1094,8 @@ transientTauDays={:1.3f}\n""")
         else:
             data_duration = self.maxStartTime - self.minStartTime
             cl_mfd.append('--duration={}'.format(int(data_duration)))
-        cl_mfd.append('--fmin={}'.format(self.fmin))
-        cl_mfd.append('--Band={}'.format(self.Band))
+        cl_mfd.append('--fmin={:.16g}'.format(self.fmin))
+        cl_mfd.append('--Band={:.16g}'.format(self.Band))
         cl_mfd.append('--Tsft={}'.format(self.Tsft))
         if self.h0 != 0:
             cl_mfd.append('--injectionSources="{}"'.format(self.config_file_name))
diff --git a/tests.py b/tests.py
index 090d50f50114ecea81e98edbb1eb36952cd7dcce..e11b5f5ddb7585dfee3db72b2192d567bafde5b4 100644
--- a/tests.py
+++ b/tests.py
@@ -31,9 +31,10 @@ class TestWriter(Test):
             './TestData/H-4800_H1_1800SFT_Test-700000000-8640000.sft'))
 
     def test_makefakedata_usecached(self):
-        Writer = pyfstat.Writer(self.label, outdir=outdir)
+        Writer = pyfstat.Writer(self.label, outdir=outdir, duration=86400)
         if os.path.isfile(Writer.sftfilepath):
             os.remove(Writer.sftfilepath)
+        Writer.make_cff()
         Writer.run_makefakedata()
         time_first = os.path.getmtime(Writer.sftfilepath)
         Writer.run_makefakedata()