diff --git a/pycbc/workflow/core.py b/pycbc/workflow/core.py
index 824d50c2d4b..e491a7812c7 100644
--- a/pycbc/workflow/core.py
+++ b/pycbc/workflow/core.py
@@ -1122,13 +1122,12 @@ def __init__(self, ifos, exe_name, segs, file_url=None,
         exe_name: string
             A short description of the executable description, tagging
             only the program that ran this job.
-        segs : igwn_segments.segment or igwn_segments.segmentlist or None
+        segs : igwn_segments.segment or igwn_segments.segmentlist
             The time span that the OutFile is valid for. Note that this is
             *not* the same as the data that the job that made the file reads in.
             Lalapps_inspiral jobs do not analyse the first an last 72s of the
             data that is read, and are therefore not valid at those times. If
             the time is not continuous a segmentlist can be supplied.
-            If None is given, the time is not used in the output filename
         file_url : url (optional, default=None)
             If this is *not* supplied, extension and directory must be given.
             If specified this explicitly points to the url of the file, or the
@@ -1286,19 +1285,13 @@ def _filename(self, ifo, description, extension, segment):
 
         # Follow the frame convention of using integer filenames,
         # but stretching to cover partially covered seconds.
-        # The if statement allows us to use a filename which doesn't
-        # have a time associated to it
         start = int(segment[0])
         end = int(math.ceil(segment[1]))
-        if (end-start) > 0 and segment[0] > 0:
-            duration = end - start
-            time_str = f"-{start}-{duration}"
-        else:
-            # This comes about when we haven't defined a time range for
-            # the file, so don't add any information
-            time_str = ""
+        duration = str(end-start)
+        start = str(start)
 
-        return "%s-%s%s.%s" % (ifo, description.upper(), time_str, extension)
+        return "%s-%s-%s-%s.%s" % (ifo, description.upper(), start,
+                                   duration, extension)
 
     @classmethod
     def from_path(cls, path, attrs=None, **kwargs):