diff --git a/adafruit_minimqtt/adafruit_minimqtt.py b/adafruit_minimqtt/adafruit_minimqtt.py
index 2d74dd92..90d3a74c 100644
--- a/adafruit_minimqtt/adafruit_minimqtt.py
+++ b/adafruit_minimqtt/adafruit_minimqtt.py
@@ -784,22 +784,34 @@ def subscribe(self, topic, qos=0):
         stamp = time.monotonic()
         while True:
             op = self._wait_for_msg()
-            if op == 0x90:
-                rc = self._sock_exact_recv(4)
-                assert rc[1] == packet[2] and rc[2] == packet[3]
-                if rc[3] == 0x80:
-                    raise MMQTTException("SUBACK Failure!")
-                for t, q in topics:
-                    if self.on_subscribe is not None:
-                        self.on_subscribe(self, self._user_data, t, q)
-                    self._subscribed_topics.append(t)
-                return
-
             if op is None:
                 if time.monotonic() - stamp > self._recv_timeout:
                     raise MMQTTException(
                         f"No data received from broker for {self._recv_timeout} seconds."
                     )
+            else:
+                if op == 0x90:
+                    rc = self._sock_exact_recv(3)
+                    # Check packet identifier.
+                    assert rc[1] == packet[2] and rc[2] == packet[3]
+                    remaining_len = rc[0] - 2
+                    assert remaining_len > 0
+                    rc = self._sock_exact_recv(remaining_len)
+                    for i in range(0, remaining_len):
+                        if rc[i] not in [0, 1, 2]:
+                            raise MMQTTException(
+                                f"SUBACK Failure for topic {topics[i][0]}: {hex(rc[i])}"
+                            )
+
+                    for t, q in topics:
+                        if self.on_subscribe is not None:
+                            self.on_subscribe(self, self._user_data, t, q)
+                        self._subscribed_topics.append(t)
+                    return
+
+                raise MMQTTException(
+                    f"invalid message received as response to SUBSCRIBE: {hex(op)}"
+                )
 
     def unsubscribe(self, topic):
         """Unsubscribes from a MQTT topic.
@@ -838,22 +850,26 @@ def unsubscribe(self, topic):
         while True:
             stamp = time.monotonic()
             op = self._wait_for_msg()
-            if op == 176:
-                rc = self._sock_exact_recv(3)
-                assert rc[0] == 0x02
-                # [MQTT-3.32]
-                assert rc[1] == packet_id_bytes[0] and rc[2] == packet_id_bytes[1]
-                for t in topics:
-                    if self.on_unsubscribe is not None:
-                        self.on_unsubscribe(self, self._user_data, t, self._pid)
-                    self._subscribed_topics.remove(t)
-                return
-
             if op is None:
                 if time.monotonic() - stamp > self._recv_timeout:
                     raise MMQTTException(
                         f"No data received from broker for {self._recv_timeout} seconds."
                     )
+            else:
+                if op == 176:
+                    rc = self._sock_exact_recv(3)
+                    assert rc[0] == 0x02
+                    # [MQTT-3.32]
+                    assert rc[1] == packet_id_bytes[0] and rc[2] == packet_id_bytes[1]
+                    for t in topics:
+                        if self.on_unsubscribe is not None:
+                            self.on_unsubscribe(self, self._user_data, t, self._pid)
+                        self._subscribed_topics.remove(t)
+                    return
+
+                raise MMQTTException(
+                    f"invalid message received as response to UNSUBSCRIBE: {hex(op)}"
+                )
 
     def _recompute_reconnect_backoff(self):
         """
@@ -992,6 +1008,7 @@ def _wait_for_msg(self, timeout=0.1):
             return MQTT_PINGRESP
 
         if res[0] & MQTT_PKT_TYPE_MASK != MQTT_PUBLISH:
+            self.logger.debug(f"Got message type: {hex(res[0])}")
             return res[0]
 
         # Handle only the PUBLISH packet type from now on.