diff --git a/liquidctl/driver/commander_core.py b/liquidctl/driver/commander_core.py
index 932ed645a..2f5626232 100644
--- a/liquidctl/driver/commander_core.py
+++ b/liquidctl/driver/commander_core.py
@@ -237,6 +237,7 @@ def _send_command(self, command, data=()):
     def _wake_device_context(self):
         try:
             self._send_command(_CMD_WAKE)
+            self._send_command(_CMD_RESET)
             yield
         finally:
             self._send_command(_CMD_SLEEP)
diff --git a/tests/test_commander_core.py b/tests/test_commander_core.py
index b8f6795f7..a23d9c611 100644
--- a/tests/test_commander_core.py
+++ b/tests/test_commander_core.py
@@ -31,7 +31,7 @@ def __init__(self):
 
         self._last_write = bytes()
         self._modes = {}
-
+        self._is_reset = False
         self._awake = False
 
         self.response_prefix = ()
@@ -52,7 +52,7 @@ def read(self, length):
         if self._awake:
             if self._last_write[2] == 0x08:  # Get data
                 channel = self._last_write[3]
-                mode = self._modes[channel]
+                mode = self._modes.get(channel)
                 if mode[1] == 0x00:
                     if mode[0] == 0x17:  # Get speeds
                         data.extend([0x06, 0x00])
@@ -114,16 +114,20 @@ def write(self, data):
 
         if data[2] == 0x0d:
             channel = data[3]
-            if self._modes[channel] is None:
+            if  (self._is_reset or not self._awake) and self._modes.get(channel) is None:
                 self._modes[channel] = data[4:6]
+                self._is_reset = False
+            else:
+                raise ExpectationNotMet('Previous channel was not reset')
         elif data[2] == 0x05 and data[3] == 0x01:
             self._modes[data[4]] = None
+            self._is_reset = True
         elif data[2] == 0x01 and data[3] == 0x03 and data[4] == 0x00:
             self._awake = data[5] == 0x02
         elif self._awake:
             if data[2] == 0x06:  # Write command
                 channel = data[3]
-                mode = self._modes[channel]
+                mode = self._modes.get(channel)
                 length = u16le_from(data[4:6])
                 data_type = data[8:10]
                 written_data = data[10:8+length]