diff --git a/nilmtools/filter.py b/nilmtools/filter.py
index 9b4c23d..b02df13 100644
--- a/nilmtools/filter.py
+++ b/nilmtools/filter.py
@@ -173,21 +173,21 @@ class Filter(object):
         self.end = None
         self._interhost = False
         self._force_metadata = False
+        self.def_url = os.environ.get("NILMDB_URL", "http://localhost/nilmdb/")
         if parser_description is not None:
             self.setup_parser(parser_description)
             self.parse_args()
-        self.def_url = os.environ.get("NILMDB_URL", "http://localhost/nilmdb/")
 
     @property
     def client_src(self):
         if self._using_client:
-            raise Exception("Filter client is in use; make another")
+            raise Exception("Filter src client is in use; make another")
         return self._client_src
 
     @property
     def client_dest(self):
         if self._using_client:
-            raise Exception("Filter client is in use; make another")
+            raise Exception("Filter dest client is in use; make another")
         return self._client_dest
 
     def setup_parser(self, description = "Filter data", skip_paths = False):
@@ -205,6 +205,9 @@ class Filter(object):
                            default = False,
                            help="Just print intervals that would be "
                            "processed")
+        group.add_argument("-q", "--quiet", action="store_true",
+                           default = False,
+                           help="Don't print source and dest stream info")
         group.add_argument("-F", "--force-metadata", action="store_true",
                            default = False,
                            help="Force metadata changes if the dest "
@@ -269,7 +272,7 @@ class Filter(object):
         args = self._parser.parse_args(argv)
 
         self.set_args(args.url, args.dest_url, args.srcpath, args.destpath,
-                      args.start, args.end, quiet = False, parsed_args = args)
+                      args.start, args.end, quiet=args.quiet, parsed_args=args)
 
         self._force_metadata = args.force_metadata
         if args.dry_run:
diff --git a/tests/test.py b/tests/test.py
index 851c0ff..14f9881 100644
--- a/tests/test.py
+++ b/tests/test.py
@@ -28,6 +28,7 @@ import traceback
 import os
 import atexit
 import signal
+import functools
 
 from urllib.request import urlopen
 from nilmtools.filter import ArgumentError
@@ -834,7 +835,77 @@ class TestAllCommands(CommandTester):
         self.ok(f"--estimate tests/data/cleanup-nodecim.cfg")
 
     def test_12_misc(self):
-        # Fill in test cases that were missed by earlier code
+        # Fill in test cases that were missed by earlier code:
+
+        # math.py
         with assert_raises(ValueError):
             nilmtools.math.sfit4([1], 5)
         nilmtools.math.sfit4([1,2], 5)
+
+        # filter.py
+        client = nilmdb.client.numpyclient.NumpyClient(self.url)
+        client.stream_create("/misc/a", "uint8_1")
+        client.stream_create("/misc/b", "uint8_1")
+        with client.stream_insert_context("/misc/a") as ctx:
+            for n in range(10000):
+                ctx.insert(b"%d 0\n" % n)
+        pni = nilmtools.filter.process_numpy_interval
+        src = nilmtools.filter.get_stream_info(client, "/misc/a")
+        extractor = functools.partial(
+            client.stream_extract_numpy, "/misc/a",
+            layout=src.layout, maxrows=1000)
+        inserter = functools.partial(
+            client.stream_insert_numpy_context, "/misc/b")
+        def func1(*args):
+            return 0
+        def func2(*args):
+            return -1
+        def func3(array, interval, args, insert_func, last):
+            if last:
+                return array.shape[0]
+            return 0
+        saved = (sys.stdout, sys.stderr)
+        try:
+            with open(os.devnull, 'w') as sys.stdout:
+                with open(os.devnull, 'w') as sys.stderr:
+                    pni(Interval(0, 10000), extractor, inserter, 100, func1)
+                    with assert_raises(SystemExit):
+                        f = nilmtools.filter.Filter("hello world")
+        finally:
+            (sys.stdout, sys.stderr) = saved
+
+        with assert_raises(Exception):
+            pni(Interval(0, 10000), extractor, inserter, 100, func2)
+        pni(Interval(0, 10000), extractor, inserter, 100000, func3)
+
+        with assert_raises(NotImplementedError):
+            pni(Interval(0, 10000), extractor, inserter, 100000,
+                nilmtools.filter.example_callback_function)
+
+        self.main = nilmtools.filter.main
+        self.fail(f"")
+        self.ok(f"--help")
+
+        self.fail(f"/misc/a /misc/a")
+        self.contain("must be different")
+
+        self.fail(f"--start HELLOWORLD /misc/a /misc/a")
+        self.contain("not enough digits for a timestamp")
+
+        client.stream_create("/misc/c", "uint8_1")
+        self.ok(f"--quiet /misc/a /misc/c")
+        self.contain("Source: /misc/a", False)
+        self.contain("Generic filter: need to handle")
+
+        f = nilmtools.filter.Filter()
+        parser = f.setup_parser()
+        args = f.parse_args(["--quiet", "/misc/a", "/misc/c"])
+        x = f.client_src
+        x = f.client_dest
+        for i in f.intervals():
+            with assert_raises(Exception) as e:
+                x = f.client_src
+            in_("client is in use", str(e.exception))
+            with assert_raises(Exception) as e:
+                x = f.client_dest
+            in_("client is in use", str(e.exception))