diff --git a/pkgs/development/python-modules/pyserial/001-rfc2217-only-negotiate-on-value-change.patch b/pkgs/development/python-modules/pyserial/001-rfc2217-only-negotiate-on-value-change.patch
new file mode 100644
index 000000000000..6bd40bd935d6
--- /dev/null
+++ b/pkgs/development/python-modules/pyserial/001-rfc2217-only-negotiate-on-value-change.patch
@@ -0,0 +1,42 @@
+From c8b35f4b871d00e3020f525425517548bed9f6ad Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
+Date: Sun, 9 Sep 2018 20:13:27 +0200
+Subject: [PATCH] serial/rfc2217: only subnegotiate on value change
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This was suggested and is a direct copy of Uwe Kleine König's patch
+from [1].
+
+[1]: https://github.com/pyserial/pyserial/issues/376#issuecomment-418885211
+Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
+---
+ serial/rfc2217.py | 14 +++++++++-----
+ 1 file changed, 9 insertions(+), 5 deletions(-)
+
+diff --git a/serial/rfc2217.py b/serial/rfc2217.py
+index d962c1e8..2148512d 100644
+--- a/serial/rfc2217.py
++++ b/serial/rfc2217.py
+@@ -330,11 +330,15 @@ def set(self, value):
+         the client needs to know if the change is performed he has to check the
+         state of this object.
+         """
+-        self.value = value
+-        self.state = REQUESTED
+-        self.connection.rfc2217_send_subnegotiation(self.option, self.value)
+-        if self.connection.logger:
+-            self.connection.logger.debug("SB Requesting {} -> {!r}".format(self.name, self.value))
++        if value != self.value:
++            self.value = value
++            self.state = REQUESTED
++            self.connection.rfc2217_send_subnegotiation(self.option, self.value)
++            if self.connection.logger:
++                self.connection.logger.debug("SB Requesting {} -> {!r}".format(self.name, self.value))
++        else:
++            if self.connection.logger:
++                self.connection.logger.debug("SB Requesting {} -> {!r} (skipped)".format(self.name, self.value))
+
+     def is_ready(self):
+         """\
diff --git a/pkgs/development/python-modules/pyserial/002-rfc2217-timeout-setter-for-rfc2217.patch b/pkgs/development/python-modules/pyserial/002-rfc2217-timeout-setter-for-rfc2217.patch
new file mode 100644
index 000000000000..39410dee1640
--- /dev/null
+++ b/pkgs/development/python-modules/pyserial/002-rfc2217-timeout-setter-for-rfc2217.patch
@@ -0,0 +1,42 @@
+From a3698dc952fce0d07628133e987b7b43ed6e1157 Mon Sep 17 00:00:00 2001
+From: Rouven Czerwinski <rouven@czerwinskis.de>
+Date: Sun, 9 Sep 2018 20:08:40 +0200
+Subject: [PATCH] serial/rfc2217: add timeout.setter for rfc2217
+
+Add a new setter method for the timeout property which does not invoke
+the port reconfiguration.
+This is a direct copy of the SerialBase timeout property without the port
+reconfiguration.
+
+Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
+---
+ serial/rfc2217.py | 17 +++++++++++++++++
+ 1 file changed, 17 insertions(+)
+
+diff --git a/serial/rfc2217.py b/serial/rfc2217.py
+index d962c1e8..12615cf3 100644
+--- a/serial/rfc2217.py
++++ b/serial/rfc2217.py
+@@ -722,5 +722,22 @@ def cd(self):
+             raise portNotOpenError
+         return bool(self.get_modem_state() & MODEMSTATE_MASK_CD)
+
++    @property
++    def timeout(self):
++        """Get the current timeout setting."""
++        return self._timeout
++
++    @timeout.setter
++    def timeout(self, timeout):
++        """Change timeout setting."""
++        if timeout is not None:
++            try:
++                timeout + 1     # test if it's a number, will throw a TypeError if not...
++            except TypeError:
++                raise ValueError("Not a valid timeout: {!r}".format(timeout))
++            if timeout < 0:
++                raise ValueError("Not a valid timeout: {!r}".format(timeout))
++        self._timeout = timeout
++
+     # - - - platform specific - - -
+     # None so far
diff --git a/pkgs/development/python-modules/pyserial/default.nix b/pkgs/development/python-modules/pyserial/default.nix
index 239568f64b76..b45b031fb84a 100644
--- a/pkgs/development/python-modules/pyserial/default.nix
+++ b/pkgs/development/python-modules/pyserial/default.nix
@@ -9,6 +9,11 @@ buildPythonPackage rec {
     sha256 = "1nyd4m4mnrz8scbfqn4zpq8gnbl4x42w5zz62vcgpzqd2waf0xrw";
   };
 
+  patches = [
+    ./001-rfc2217-only-negotiate-on-value-change.patch
+    ./002-rfc2217-timeout-setter-for-rfc2217.patch
+  ];
+
   checkPhase = "python -m unittest discover -s test";
   doCheck = !stdenv.hostPlatform.isDarwin; # broken on darwin