diff --git a/pycoax/coax/protocol.py b/pycoax/coax/protocol.py
index b70a4aa..b817ac0 100644
--- a/pycoax/coax/protocol.py
+++ b/pycoax/coax/protocol.py
@@ -66,7 +66,7 @@ class PowerOnResetCompletePollResponse(PollResponse):
 
     def __init__(self, value):
         if not PollResponse.is_power_on_reset_complete(value):
-            raise ValueError('Invalid POR poll response')
+            raise ValueError(f'Invalid POR poll response: {value}')
 
         super().__init__(value)
 
@@ -75,7 +75,7 @@ class KeystrokePollResponse(PollResponse):
 
     def __init__(self, value):
         if not PollResponse.is_keystroke(value):
-            raise ValueError('Invalid keystroke poll response')
+            raise ValueError(f'Invalid keystroke poll response: {value}')
 
         super().__init__(value)
 
@@ -122,7 +122,7 @@ class TerminalId:
             model = (value & 0x0e) >> 1
 
             if model not in TerminalId._MODEL_MAP:
-                raise ValueError('Invalid model')
+                raise ValueError(f'Invalid model: {model}')
 
             self.model = TerminalId._MODEL_MAP[model]
             self.keyboard = (value & 0xf0) >> 4
@@ -131,7 +131,7 @@ class TerminalId:
             self.model = None
             self.keyboard = None
         else:
-            raise ValueError('Invalid terminal identifier')
+            raise ValueError(f'Invalid terminal identifier: {value}')
 
     def __repr__(self):
         return (f'<TerminalId type={self.type.name}, model={self.model}, '
@@ -337,7 +337,7 @@ def is_command_word(word):
 def unpack_command_word(word):
     """Unpack a 10-bit command word."""
     if not is_command_word(word):
-        raise ProtocolError('Word does not have command bit set')
+        raise ProtocolError(f'Word does not have command bit set: {word}')
 
     command = (word >> 2) & 0x1f
 
@@ -356,13 +356,13 @@ def is_data_word(word):
 def unpack_data_word(word, check_parity=False):
     """Unpack the data byte from a 10-bit data word."""
     if not is_data_word(word):
-        raise ProtocolError('Word does not have data bit set')
+        raise ProtocolError(f'Word does not have data bit set: {word}')
 
     byte = (word >> 2) & 0xff
     parity = (word >> 1) & 0x1
 
     if check_parity and parity != odd_parity(byte):
-        raise ProtocolError('Parity error')
+        raise ProtocolError(f'Parity error: {word}')
 
     return byte
 
@@ -387,7 +387,8 @@ def _execute_read_command(interface, command_word, response_length=1,
     if validate_response_length and len(response) != response_length:
         command = unpack_command_word(command_word)
 
-        raise ProtocolError(f'Expected {response_length} word {command.name} response')
+        raise ProtocolError((f'Expected {response_length} word {command.name} '
+                             f'response: {response}'))
 
     return unpack_data_words(response) if unpack else response
 
@@ -409,7 +410,7 @@ def _execute_write_command(interface, command_word, data=None, **kwargs):
     if len(response) != 1:
         command = unpack_command_word(command_word)
 
-        raise ProtocolError(f'Expected 1 word {command.name} response')
+        raise ProtocolError(f'Expected 1 word {command.name} response: {response}')
 
     if response[0] != 0:
-        raise ProtocolError('Expected TR/TA response')
+        raise ProtocolError(f'Expected TR/TA response: {response}')
diff --git a/pycoax/coax/serial_interface.py b/pycoax/coax/serial_interface.py
index 43602be..b632507 100644
--- a/pycoax/coax/serial_interface.py
+++ b/pycoax/coax/serial_interface.py
@@ -36,7 +36,7 @@ class SerialInterface(Interface):
             raise _convert_error(message)
 
         if len(message) != 4:
-            raise InterfaceError('Invalid reset response')
+            raise InterfaceError(f'Invalid reset response: {message}')
 
         (major, minor, patch) = struct.unpack('BBB', message[1:])
 
@@ -109,7 +109,7 @@ class SerialInterface(Interface):
             raise InterfaceError('SLIP protocol error')
 
         if len(message) < 4:
-            raise InterfaceError('Invalid response message')
+            raise InterfaceError(f'Invalid response message: {message}')
 
         (length,) = struct.unpack('>H', message[:2])
 
@@ -156,15 +156,15 @@ ERROR_MAP = {
 
 def _convert_error(message):
     if message[0] != 0x02:
-        return InterfaceError('Invalid response')
+        return InterfaceError(f'Invalid response: {message}')
 
     if len(message) < 2:
-        return InterfaceError('Invalid error response')
+        return InterfaceError(f'Invalid error response: {message}')
 
     if message[1] in ERROR_MAP:
         return ERROR_MAP[message[1]]
 
-    return InterfaceError('Unknown error')
+    return InterfaceError(f'Unknown error: {message[1]}')
 
 class SlipSerial(SlipWrapper):
     """sliplib wrapper for pySerial."""