diff --git a/edosl0util/cli/rdr2l0.py b/edosl0util/cli/rdr2l0.py
index e595f1c967f8dbaa7f2ebe2aeb619b3a04382ced..d40814c7e507185f0ced477be1a1953f8d7bcbb5 100644
--- a/edosl0util/cli/rdr2l0.py
+++ b/edosl0util/cli/rdr2l0.py
@@ -32,11 +32,6 @@ def main():
     parser.add_argument(
         '--ancillary', action='store_true',
         help='Dump spacecraft ancillary datasets')
-    """
-    parser.add_argument(
-        '--skipfill', action='store_true',
-        help='Skip any packets marked as containing fill in the RDR')
-    """
     def timestamp(v):
         return datetime.strptime(v, '%Y-%m-%d %H:%M:%S')
     parser.add_argument(
@@ -52,17 +47,8 @@ def main():
     def remove_files(files):
         [os.remove(f) for f in files]
 
-    science_products = {
-        'RNSCA-RVIRS': '0826VIIRSSCIENCE',
-        'RCRIS-RNSCA': '1289CRISSCIENCEA',
-        'RATMS-RNSCA': '0515ATMSSCIENCEA'}
-
-    file_type = os.path.basename(args.rdr[0]).split('_')[0]
-    LOG.info('File type %s', file_type)
     for filepath in args.rdr:
         dirname, rdrname = os.path.split(filepath)
-        if not rdrname.startswith(file_type):
-            raise ValueError('All rdrs must have same file type', rdrname)
         LOG.info("dumping %s", filepath)
         jpssrdr.write_rdr_datasets(
             filepath,
@@ -79,11 +65,22 @@ def main():
             product = '{:04d}AAAAAAAAAAA'.format(apid)
             pdsname = pdsfilename(product)
             LOG.info("merging apid %d to %s", apid, pdsname)
-            streams = [stream.jpss_packet_stream(open(f, 'rb')) for f in inputs]
-            merge.merge(streams, output=open(pdsname, 'wb'), trunc_to=interval)
+            # there are potentially a very large number of inputs (RNSCA) so
+            # make sure to keep track of files so we can explicitly close them
+            files = [open(f, 'rb') for f in inputs]
+            streams = [stream.jpss_packet_stream(f) for f in files]
+            with open(pdsname, 'wb') as dest:
+                merge.merge(streams, output=dest, trunc_to=interval)
+            for f in files:
+                f.close()
             remove_files(inputs)
 
+    science_products = {
+        'RNSCA-RVIRS': '0826VIIRSSCIENCE',
+        'RCRIS-RNSCA': '1289CRISSCIENCEA',
+        'RATMS-RNSCA': '0515ATMSSCIENCEA'}
     if args.science:
+        file_type = os.path.basename(args.rdr[0]).split('_')[0]
         if file_type not in science_products:
             parser.exit(1, '%s is not a supported science file type\n' % file_type)
         inputs = sorted(glob.glob('*.science.pkts'))
@@ -91,7 +88,8 @@ def main():
         pdsname = pdsfilename(product)
         LOG.info("merging %s to %s", product, pdsname)
         streams = [stream.jpss_packet_stream(open(f, 'rb')) for f in inputs]
-        merge.merge(streams, output=open(pdsname, 'wb'), trunc_to=interval)
+        with open(pdsname, 'wb') as dest:
+            merge.merge(streams, output=dest, trunc_to=interval)
         remove_files(inputs)
 
 
diff --git a/edosl0util/jpssrdr.py b/edosl0util/jpssrdr.py
index d27866bebff433303bea7654aad558ef1f3c482e..71a8d3652b6a265d2c4a68706cbd3d421f949807 100644
--- a/edosl0util/jpssrdr.py
+++ b/edosl0util/jpssrdr.py
@@ -163,6 +163,7 @@ def _find_science_group(fobj):
 
 
 def _rdrs_for_packet_dataset(group):
+    rdrs = []
     if group:
         for name, buf in _generate_packet_datasets(group):
             if buf.shape[0] < c.sizeof(StaticHeader):
@@ -170,16 +171,17 @@ def _rdrs_for_packet_dataset(group):
                 continue
             header = StaticHeader.from_buffer(buf)
             apids = _read_apid_list(header, buf)
-            yield CommonRdr(buf, header, list(apids))
+            rdrs.append(CommonRdr(buf, header, list(apids)))
+    return rdrs
 
 
 def rdr_datasets(filepath):
     fobj = H5File(filepath)
     rdr = {}
-    group = _find_science_group(fobj)
-    rdr['science'] = _rdrs_for_packet_dataset(group)
-    group = fobj.get('/All_Data/SPACECRAFT-DIARY-RDR_All')
-    rdr['ancillary'] = _rdrs_for_packet_dataset(group)
+    rdr['science'] = _rdrs_for_packet_dataset(_find_science_group(fobj))
+    rdr['ancillary'] = _rdrs_for_packet_dataset(
+        fobj.get('/All_Data/SPACECRAFT-DIARY-RDR_All'))
+    fobj.close()
     return rdr
 
 
@@ -234,12 +236,12 @@ def write_rdr_datasets(filepath, science=True, ancillary=True, skipfill=False):
 
     if ancillary:
         for idx, rdr in enumerate(rdrs['ancillary']):
-            packets = {a.value: rdr.packets_for_apid(a.value)
+            packets = {a.value: rdr.packets_for_apid(a)
                        for a in rdr.apids}
-            for apid, packets in packets.items():
+            for apid, pkts in packets.items():
                 LOG.debug(
                     'writing ancillary gran %d %s-%s-%s %d',
                     idx, rdr.header.satellite, rdr.header.sensor,
-                    rdr.header.type_id, apid.value)
+                    rdr.header.type_id, apid)
                 with open('{}.anc{}.pkts'.format(rdrname, apid), 'wb') as dest:
-                    _write_packets(packets, dest)
+                    _write_packets(pkts, dest, skipfill)