diff --git a/mitmproxy/optmanager.py b/mitmproxy/optmanager.py
index 081836ce6..e497c3b6a 100644
--- a/mitmproxy/optmanager.py
+++ b/mitmproxy/optmanager.py
@@ -180,12 +180,13 @@ class OptManager(metaclass=_DefaultsMeta):
             Save to path. If the destination file exists, modify it in-place.
         """
         if os.path.exists(path) and os.path.isfile(path):
-            data = open(path, "r").read()
+            with open(path, "r") as f:
+                data = f.read()
         else:
             data = ""
         data = self.serialize(data, defaults)
-        fp = open(path, "w")
-        fp.write(data)
+        with open(path, "w") as f:
+            f.write(data)
 
     def serialize(self, text, defaults=False):
         """
@@ -228,8 +229,7 @@ class OptManager(metaclass=_DefaultsMeta):
             this object. May raise OptionsError if the config file is invalid.
         """
         data = self._load(text)
-        for k, v in data.items():
-            setattr(self, k, v)
+        self.update(**data)
 
     def load_paths(self, *paths):
         """
@@ -240,7 +240,8 @@ class OptManager(metaclass=_DefaultsMeta):
         for p in paths:
             p = os.path.expanduser(p)
             if os.path.exists(p) and os.path.isfile(p):
-                txt = open(p, "r").read()
+                with open(p, "r") as f:
+                    txt = f.read()
                 self.load(txt)
 
     def __repr__(self):
diff --git a/mitmproxy/tools/cmdline.py b/mitmproxy/tools/cmdline.py
index 1cdde727f..925491d7d 100644
--- a/mitmproxy/tools/cmdline.py
+++ b/mitmproxy/tools/cmdline.py
@@ -513,6 +513,7 @@ def proxy_ssl_options(parser):
              'as the first entry. Can be passed multiple times.')
     group.add_argument(
         "--ciphers-client", action="store",
+        type=str, dest="ciphers_client",
         help="Set supported ciphers for client connections. (OpenSSL Syntax)"
     )
     group.add_argument(
diff --git a/test/mitmproxy/addons/test_dumper.py b/test/mitmproxy/addons/test_dumper.py
index f87df3295..760efa08d 100644
--- a/test/mitmproxy/addons/test_dumper.py
+++ b/test/mitmproxy/addons/test_dumper.py
@@ -31,37 +31,37 @@ def test_simple():
     sio = io.StringIO()
     d = dumper.Dumper(sio)
     with taddons.context(options=dump.Options()) as ctx:
-        ctx.configure(d, flow_detail = 0)
+        ctx.configure(d, flow_detail=0)
         d.response(tflow.tflow(resp=True))
         assert not sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 1)
+        ctx.configure(d, flow_detail=1)
         d.response(tflow.tflow(resp=True))
         assert sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 1)
+        ctx.configure(d, flow_detail=1)
         d.error(tflow.tflow(err=True))
         assert sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         d.response(tflow.tflow(resp=True))
         assert sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         d.response(tflow.tflow(resp=True))
         assert "<<" in sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         d.response(tflow.tflow(err=True))
         assert "<<" in sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         flow = tflow.tflow()
         flow.request = tutils.treq()
         flow.request.stickycookie = True
@@ -74,7 +74,7 @@ def test_simple():
         assert sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         flow = tflow.tflow(resp=tutils.tresp(content=b"{"))
         flow.response.headers["content-type"] = "application/json"
         flow.response.status_code = 400
@@ -82,7 +82,7 @@ def test_simple():
         assert sio.getvalue()
         sio.truncate(0)
 
-        ctx.configure(d, flow_detail = 4)
+        ctx.configure(d, flow_detail=4)
         flow = tflow.tflow()
         flow.request.content = None
         flow.response = http.HTTPResponse.wrap(tutils.tresp())
@@ -100,7 +100,7 @@ def test_echo_body():
     sio = io.StringIO()
     d = dumper.Dumper(sio)
     with taddons.context(options=dump.Options()) as ctx:
-        ctx.configure(d, flow_detail = 3)
+        ctx.configure(d, flow_detail=3)
         d._echo_message(f.response)
         t = sio.getvalue()
         assert "cut off" in t
@@ -110,7 +110,7 @@ def test_echo_request_line():
     sio = io.StringIO()
     d = dumper.Dumper(sio)
     with taddons.context(options=dump.Options()) as ctx:
-        ctx.configure(d, flow_detail = 3, showhost = True)
+        ctx.configure(d, flow_detail=3, showhost=True)
         f = tflow.tflow(client_conn=None, server_conn=True, resp=True)
         f.request.is_replay = True
         d._echo_request_line(f)
@@ -146,7 +146,7 @@ def test_tcp():
     sio = io.StringIO()
     d = dumper.Dumper(sio)
     with taddons.context(options=dump.Options()) as ctx:
-        ctx.configure(d, flow_detail = 3, showhost = True)
+        ctx.configure(d, flow_detail=3, showhost=True)
         f = tflow.ttcpflow(client_conn=True, server_conn=True)
         d.tcp_message(f)
         assert "it's me" in sio.getvalue()
diff --git a/test/mitmproxy/test_optmanager.py b/test/mitmproxy/test_optmanager.py
index 0c98daea0..c6eb25345 100644
--- a/test/mitmproxy/test_optmanager.py
+++ b/test/mitmproxy/test_optmanager.py
@@ -15,7 +15,7 @@ class TO(optmanager.OptManager):
 
 
 class TD(optmanager.OptManager):
-    def __init__(self, one="done", two="dtwo", three="error"):
+    def __init__(self, *, one="done", two="dtwo", three="error"):
         self.one = one
         self.two = two
         self.three = three