diff --git a/umodbus/client/serial/rtu.py b/umodbus/client/serial/rtu.py
index 4c01580..c94ed20 100644
--- a/umodbus/client/serial/rtu.py
+++ b/umodbus/client/serial/rtu.py
@@ -53,6 +53,7 @@
                                WriteSingleRegister, WriteMultipleCoils,
                                WriteMultipleRegisters)
 from umodbus.utils import recv_exactly
+from umodbus.exceptions import ModbusFrameError
 
 
 def _create_request_adu(slave_id, req_pdu):
@@ -173,9 +174,9 @@ def write_multiple_registers(slave_id, starting_address, values):
 
 def parse_response_adu(resp_adu, req_adu=None):
     """ Parse response ADU and return response data. Some functions require
-    request ADU to fully understand request ADU.
+    request ADU to fully understand response ADU.
 
-    :param resp_adu: Resonse ADU.
+    :param resp_adu: Response ADU.
     :param req_adu: Request ADU, default None.
     :return: Response data.
     """
@@ -217,6 +218,10 @@ def send_message(adu, serial_port):
     response_error_adu = recv_exactly(serial_port.read, exception_adu_size)
     raise_for_exception_adu(response_error_adu)
 
+    if response_error_adu[0:2] != adu[0:2]:
+        # Mismatch in response's slave address or function code
+        raise ModbusFrameError(response_error_adu)
+
     expected_response_size = \
         expected_response_pdu_size_from_request_pdu(adu[1:-2]) + 3
     response_remainder = recv_exactly(
diff --git a/umodbus/exceptions.py b/umodbus/exceptions.py
index 85a9a56..57f74f8 100644
--- a/umodbus/exceptions.py
+++ b/umodbus/exceptions.py
@@ -3,6 +3,12 @@ class ModbusError(Exception):
     pass
 
 
+class ModbusFrameError(ModbusError):
+    """Reply from an unexpected slave, or an error in the received frame."""
+
+    pass
+
+
 class IllegalFunctionError(ModbusError):
     """ The function code received in the request is not an allowable action for
     the server.