diff --git a/adafruit_minimqtt/adafruit_minimqtt.py b/adafruit_minimqtt/adafruit_minimqtt.py
index 53e98011..0cbc2667 100644
--- a/adafruit_minimqtt/adafruit_minimqtt.py
+++ b/adafruit_minimqtt/adafruit_minimqtt.py
@@ -267,40 +267,76 @@ def mqtt_msg(self, msg_size: int) -> None:
         if msg_size < MQTT_MSG_MAX_SZ:
             self._msg_size_lim = msg_size
 
+    # pylint: disable=too-many-branches, too-many-statements
     def will_set(
         self,
-        topic: Optional[str] = None,
-        payload: Optional[Union[int, float, str]] = None,
-        qos: int = 0,
+        topic: str,
+        msg: Union[str, int, float, bytes],
         retain: bool = False,
+        qos: int = 0,
     ) -> None:
         """Sets the last will and testament properties. MUST be called before `connect()`.
 
         :param str topic: MQTT Broker topic.
-        :param int|float|str payload: Last will disconnection payload.
-            payloads of type int & float are converted to a string.
+        :param str|int|float|bytes msg: Last will disconnection msg.
+            msgs of type int & float are converted to a string.
+            msgs of type byetes are left unchanged, as it is in the publish function.
         :param int qos: Quality of Service level, defaults to
             zero. Conventional options are ``0`` (send at most once), ``1``
             (send at least once), or ``2`` (send exactly once).
-
             .. note:: Only options ``1`` or ``0`` are QoS levels supported by this library.
-        :param bool retain: Specifies if the payload is to be retained when
+        :param bool retain: Specifies if the msg is to be retained when
             it is published.
         """
         self.logger.debug("Setting last will properties")
-        self._valid_qos(qos)
         if self._is_connected:
             raise MMQTTException("Last Will should only be called before connect().")
-        if payload is None:
-            payload = ""
-        if isinstance(payload, (int, float, str)):
-            payload = str(payload).encode()
+
+        # check topic/msg/qos kwargs
+        self._valid_topic(topic)
+        if "+" in topic or "#" in topic:
+            raise MMQTTException("Publish topic can not contain wildcards.")
+
+        if msg is None:
+            raise MMQTTException("Message can not be None.")
+        if isinstance(msg, (int, float)):
+            msg = str(msg).encode("ascii")
+        elif isinstance(msg, str):
+            msg = str(msg).encode("utf-8")
+        elif isinstance(msg, bytes):
+            pass
         else:
             raise MMQTTException("Invalid message data type.")
+        if len(msg) > MQTT_MSG_MAX_SZ:
+            raise MMQTTException(f"Message size larger than {MQTT_MSG_MAX_SZ} bytes.")
+
+        self._valid_qos(qos)
+        assert (
+            0 <= qos <= 1
+        ), "Quality of Service Level 2 is unsupported by this library."
+
+        # fixed header. [3.3.1.2], [3.3.1.3]
+        pub_hdr_fixed = bytearray([MQTT_PUBLISH | retain | qos << 1])
+
+        # variable header = 2-byte Topic length (big endian)
+        pub_hdr_var = bytearray(struct.pack(">H", len(topic.encode("utf-8"))))
+        pub_hdr_var.extend(topic.encode("utf-8"))  # Topic name
+
+        remaining_length = 2 + len(msg) + len(topic.encode("utf-8"))
+        if qos > 0:
+            # packet identifier where QoS level is 1 or 2. [3.3.2.2]
+            remaining_length += 2
+            self._pid = self._pid + 1 if self._pid < 0xFFFF else 1
+            pub_hdr_var.append(self._pid >> 8)
+            pub_hdr_var.append(self._pid & 0xFF)
+
+        self._encode_remaining_length(pub_hdr_fixed, remaining_length)
+
         self._lw_qos = qos
         self._lw_topic = topic
-        self._lw_msg = payload
+        self._lw_msg = msg
         self._lw_retain = retain
+        self.logger.debug("Last will properties successfully set")
 
     def add_topic_callback(self, mqtt_topic: str, callback_method) -> None:
         """Registers a callback_method for a specific MQTT topic.
diff --git a/adafruit_minimqtt/matcher.py b/adafruit_minimqtt/matcher.py
index c14a3514..1162d3c4 100644
--- a/adafruit_minimqtt/matcher.py
+++ b/adafruit_minimqtt/matcher.py
@@ -88,11 +88,9 @@ def rec(node: MQTTMatcher.Node, i: int = 0):
             else:
                 part = lst[i]
                 if part in node.children:
-                    for content in rec(node.children[part], i + 1):
-                        yield content
+                    yield from rec(node.children[part], i + 1)
                 if "+" in node.children and (normal or i > 0):
-                    for content in rec(node.children["+"], i + 1):
-                        yield content
+                    yield from rec(node.children["+"], i + 1)
             if "#" in node.children and (normal or i > 0):
                 content = node.children["#"].content
                 if content is not None: