diff --git a/gstlal-inspiral/bin/gstlal_inspiral_create_dt_dphi_snr_ratio_pdfs b/gstlal-inspiral/bin/gstlal_inspiral_create_dt_dphi_snr_ratio_pdfs
index d67c9b6b2119abc5d2a9889a4a69f08449670a8a..4e4477a10cebc216913d4f35dbf5f14367e7985c 100755
--- a/gstlal-inspiral/bin/gstlal_inspiral_create_dt_dphi_snr_ratio_pdfs
+++ b/gstlal-inspiral/bin/gstlal_inspiral_create_dt_dphi_snr_ratio_pdfs
@@ -19,9 +19,17 @@
 import sys
 from gstlal.stats import inspiral_extrinsics
 
-if len(sys.argv) > 1:
-	print "USAGE: %s" % sys.argv[0]
+if len(sys.argv) != 1 and len(sys.argv) != 3:
+	print "USAGE: %s <marg start> <marg stop>" % sys.argv[0]
 	sys.exit()
 
-IE = inspiral_extrinsics.TimePhaseSNR(verbose = True)
-IE.to_hdf5("inspiral_dtdphi_pdf.h5")
+if len(sys.argv) == 3:
+	start = int(sys.argv[1])
+	stop = int(sys.argv[2])
+	if start % 50 or stop % 50:
+		raise ValueError("start and stop must be multiple of 50")
+	IE = inspiral_extrinsics.TimePhaseSNR(verbose = True, margstart = start, margstop = stop)
+	IE.to_hdf5("inspiral_dtdphi_%d_%d_pdf.h5" % (start, stop))
+else:
+	IE = inspiral_extrinsics.TimePhaseSNR(verbose = True)
+	IE.to_hdf5("inspiral_dtdphi_pdf.h5")