diff --git a/test/tpm_test/crypto_test.py b/test/tpm_test/crypto_test.py
index 7fa4ea6146..929df7c48c 100644
--- a/test/tpm_test/crypto_test.py
+++ b/test/tpm_test/crypto_test.py
@@ -17,9 +17,6 @@ import utils
 DECRYPT = 0
 ENCRYPT = 1
 
-class CryptoError(Exception):
-  pass
-
 def get_attribute(tdesc, attr_name, required=True):
   """Retrieve an attribute value from an XML node.
 
@@ -33,8 +30,8 @@ def get_attribute(tdesc, attr_name, required=True):
   Returns:
     The attribute value as a string (ascii or binary)
   Raises:
-    CryptoError: on various format errors, or in case a required attribute is
-      not found, the error message describes the problem.
+    subcmd.TpmTestError: on various format errors, or in case a required
+      attribute is not found, the error message describes the problem.
 
   """
   # Fields stored in hex format by default.
@@ -43,7 +40,7 @@ def get_attribute(tdesc, attr_name, required=True):
   data = tdesc.find(attr_name)
   if data is None:
     if required:
-      raise CryptoError('node "%s" does not have attribute "%s"' %
+      raise subcmd.TpmTestError('node "%s" does not have attribute "%s"' %
                         (tdesc.get('name'), attr_name))
     return ''
 
@@ -55,7 +52,7 @@ def get_attribute(tdesc, attr_name, required=True):
     else:
       cell_format = 'ascii'
   elif cell_format not in ('hex', 'ascii'):
-    raise CryptoError('%s:%s, unrecognizable format "%s"' %
+    raise subcmd.TpmTestError('%s:%s, unrecognizable format "%s"' %
                       (tdesc.get('name'), attr_name, cell_format))
 
   text = ' '.join(x.strip() for x in data.text.splitlines() if x)
@@ -65,7 +62,7 @@ def get_attribute(tdesc, attr_name, required=True):
   # Drop spaces from hex representation.
   text = text.replace(' ', '')
   if len(text) & 3:
-    raise CryptoError('%s:%s %swrong hex number size' %
+    raise subcmd.TpmTestError('%s:%s %swrong hex number size' %
                       (tdesc.get('name'), attr_name, utils.hex_dump(text)))
   # Convert text to binary
   value = ''
@@ -73,7 +70,7 @@ def get_attribute(tdesc, attr_name, required=True):
     try:
       value += struct.pack('<I', int('0x%s' % text[8*x:8*(x+1)], 16))
     except ValueError:
-      raise CryptoError('%s:%s %swrong hex value' %
+      raise subcmd.TpmTestError('%s:%s %swrong hex value' %
                         (tdesc.get('name'), attr_name, utils.hex_dump(text)))
   return value
 
@@ -134,15 +131,16 @@ def crypto_run(node_name, op_type, key, iv, in_text, out_text, tpm):
     comparison with the expected value was successful.
 
   Raises:
-    CryptoError: in case there were problems parsing the node name, or verifying
-      the operation results.
+    subcmd.TpmTestError: in case there were problems parsing the node name, or
+      verifying the operation results.
+
   """
   mode_name, submode_name = node_name.split(':')
   submode_name = submode_name[:3].upper()
 
   mode = SUPPORTED_MODES.get(mode_name.upper())
   if not mode:
-    raise CryptoError('unrecognizable mode in node "%s"' % node_name)
+    raise subcmd.TpmTestError('unrecognizable mode in node "%s"' % node_name)
 
   submode = mode.submodes.get(submode_name, 0)
   cmd = '%c' % op_type    # Encrypt or decrypt
@@ -166,12 +164,13 @@ def crypto_run(node_name, op_type, key, iv, in_text, out_text, tpm):
       if tpm.debug_enabled():
         print('Out text mismatch in node %s:\n' % node_name)
       else:
-        raise CryptoError('Out text mismatch in node %s, operation %d:\n'
-                          'In text:%sExpected out text:%sReal out text:%s' % (
-                              node_name, op_type,
-                              utils.hex_dump(in_text),
-                              utils.hex_dump(out_text),
-                              utils.hex_dump(real_out_text)))
+        raise subcmd.TpmTestError(
+          'Out text mismatch in node %s, operation %d:\n'
+          'In text:%sExpected out text:%sReal out text:%s' % (
+            node_name, op_type,
+            utils.hex_dump(in_text),
+            utils.hex_dump(out_text),
+            utils.hex_dump(real_out_text)))
   return real_out_text
 
 
@@ -187,18 +186,19 @@ def crypto_test(tdesc, tpm):
       session.
     tpm: a TPM object to send extended commands to an initialized TPM
   Raises:
-    CryptoError: on various execution errors, the details are included in the
-      error message.
+    subcmd.TpmTestError: on various execution errors, the details are included
+      in the error message.
+
   """
   node_name = tdesc.get('name')
   key = get_attribute(tdesc, 'key')
   if len(key) not in (16, 24, 32):
-    raise CryptoError('wrong key size "%s:%s"' % (
+    raise subcmd.TpmTestError('wrong key size "%s:%s"' % (
         node_name,
         ''.join('%2.2x' % ord(x) for x in key)))
   iv = get_attribute(tdesc, 'iv', required=False)
   if iv and len(iv) != 16:
-    raise CryptoError('wrong iv size "%s:%s"' % (
+    raise subcmd.TpmTestError('wrong iv size "%s:%s"' % (
         node_name,
         ''.join('%2.2x' % ord(x) for x in iv)))
   clear_text = get_attribute(tdesc, 'clear_text')
diff --git a/test/tpm_test/ecc_test.py b/test/tpm_test/ecc_test.py
index cd4bb0a261..de7f7e2d64 100644
--- a/test/tpm_test/ecc_test.py
+++ b/test/tpm_test/ecc_test.py
@@ -108,10 +108,6 @@ _KEYDERIVE_INPUTS = (
 )
 
 
-class ECError(Exception):
-  pass
-
-
 def _sign_test(tpm):
   msg = 'Hello CR50'
 
@@ -129,7 +125,7 @@ def _sign_test(tpm):
     verified = tpm.unwrap_ext_response(subcmd.EC, wrapped_response)
     expected = '\x01'
     if verified != expected:
-      raise ECError('%s error:%s:%s' % (
+      raise subcmd.TpmTestError('%s error:%s:%s' % (
         test_name, utils.hex_dump(verified), utils.hex_dump(expected)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
 
@@ -143,7 +139,7 @@ def _keygen_test(tpm):
     valid = tpm.unwrap_ext_response(subcmd.EC, wrapped_response)
     expected = '\x01'
     if valid != expected:
-      raise ECError('%s error:%s:%s' % (
+      raise subcmd.TpmTestError('%s error:%s:%s' % (
         test_name, utils.hex_dump(valid), utils.hex_dump(expected)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
 
@@ -158,7 +154,7 @@ def _keyderive_test(tpm):
     valid = tpm.unwrap_ext_response(subcmd.EC, wrapped_response)
     expected = '\x01'
     if valid != expected:
-      raise ECError('%s error:%s:%s' % (
+      raise subcmd.TpmTestError('%s error:%s:%s' % (
         test_name, utils.hex_dump(valid), utils.hex_dump(expected)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
 
diff --git a/test/tpm_test/hash_test.py b/test/tpm_test/hash_test.py
index a5a1e522c7..66c5fbf00b 100644
--- a/test/tpm_test/hash_test.py
+++ b/test/tpm_test/hash_test.py
@@ -23,10 +23,6 @@ CMD_SINGLE = 3
 MODE_SHA1 = 0
 MODE_SHA256 = 1
 
-
-class HashError(Exception):
-  pass
-
 # A standard empty response to HASH extended commands.
 EMPTY_RESPONSE = ''.join('%c' % x for x in (0x80, 0x01, 0x00, 0x00, 0x00, 0x0c,
                                             0xba, 0xcc, 0xd0, 0x0a, 0x00, 0x01))
@@ -64,7 +60,7 @@ def hash_test(tpm):
     tpm: a tpm object used to communicate with the device
 
   Raises:
-    HashError: on unexpected target responses
+    subcmd.TpmTestError: on unexpected target responses
   """
 
   contexts = {}
@@ -100,7 +96,7 @@ def hash_test(tpm):
       h = contexts[handle]
       h.update(text)
       if wrapped_response != EMPTY_RESPONSE:
-        raise HashError("Unexpected response to '%s': %s" %
+        raise subcmd.TpmTestError("Unexpected response to '%s': %s" %
                         (test_name, utils.hex_dump(wrapped_response)))
       continue
     if hash_cmd == CMD_FINISH:
@@ -108,12 +104,12 @@ def hash_test(tpm):
     elif hash_cmd == CMD_SINGLE:
       h = hash_func()
     else:
-      raise HashError('Unknown command %d' % hash_cmd)
+      raise subcmd.TpmTestError('Unknown command %d' % hash_cmd)
     h.update(text)
     digest = h.digest()
     result = wrapped_response[12:]
     if result != h.digest():
-      raise HashError('%s error:%s%s' % (test_name,
+      raise subcmd.TpmTestError('%s error:%s%s' % (test_name,
                                          utils.hex_dump(digest),
                                          utils.hex_dump(result)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
diff --git a/test/tpm_test/rsa_test.py b/test/tpm_test/rsa_test.py
index c337c524cc..0783f957fd 100644
--- a/test/tpm_test/rsa_test.py
+++ b/test/tpm_test/rsa_test.py
@@ -119,10 +119,6 @@ _SIGN_INPUTS = (
 )
 
 
-class RSAError(Exception):
-  pass
-
-
 def _encrypt_tests(tpm):
   msg = 'Hello CR50!'
 
@@ -138,7 +134,7 @@ def _encrypt_tests(tpm):
     wrapped_response = tpm.command(tpm.wrap_ext_command(subcmd.RSA, cmd))
     plaintext = tpm.unwrap_ext_response(subcmd.RSA, wrapped_response)
     if msg != plaintext:
-      raise RSAError('%s error:%s%s' % (
+      raise subcmd.TpmTestError('%s error:%s%s' % (
           test_name, utils.hex_dump(msg), utils.hex_dump(plaintext)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
 
@@ -159,7 +155,7 @@ def _sign_tests(tpm):
     verified = tpm.unwrap_ext_response(subcmd.RSA, wrapped_response)
     expected = '\x01'
     if verified != expected:
-      raise RSAError('%s error:%s%s' % (
+      raise subcmd.TpmTestError('%s error:%s%s' % (
           test_name, utils.hex_dump(verified), utils.hex_dump(expected)))
     print('%sSUCCESS: %s' % (utils.cursor_back(), test_name))
 
diff --git a/test/tpm_test/subcmd.py b/test/tpm_test/subcmd.py
index d14c2e9b9c..916767222d 100644
--- a/test/tpm_test/subcmd.py
+++ b/test/tpm_test/subcmd.py
@@ -10,3 +10,8 @@ AES = 0
 HASH = 1
 RSA = 2
 EC = 3
+
+
+# The same exception class used by all tpmtest modules.
+class TpmTestError(Exception):
+  pass
diff --git a/test/tpm_test/tpmtest.py b/test/tpm_test/tpmtest.py
index 173f0ec693..46c03ef23b 100755
--- a/test/tpm_test/tpmtest.py
+++ b/test/tpm_test/tpmtest.py
@@ -29,9 +29,6 @@ import subcmd
 # Extension command for dcypto testing
 EXT_CMD = 0xbaccd00a
 
-class TpmError(Exception):
-  pass
-
 
 class TPM(object):
   """TPM accessor class.
@@ -55,11 +52,11 @@ class TPM(object):
     self._debug_enabled = debug_mode
     self._handle = ftdi_spi_tpm
     if not self._handle.FtdiSpiInit(freq, debug_mode):
-      raise TpmError()
+      raise subcmd.TpmTestError('Failed to connect')
     response = self.command(''.join('%c' % int('0x%s' % x, 16)
                                     for x in self.STARTUP_CMD.split()))
     if ' '.join('%2.2x' % ord(x) for x in response) not in self.STARTUP_RSP:
-      raise TpmError('init failed')
+      raise subcmd.TpmTestError('init failed')
 
   def validate(self, data_blob, response_mode=False):
     """Check if a data blob complies with TPM command/response header format."""
@@ -67,12 +64,12 @@ class TPM(object):
         self.HEADER_FMT, data_blob + '  ')
     prefix = 'Misformatted blob: '
     if tag not in (0x8001, 0x8002):
-      raise TpmError(prefix + 'bad tag value 0x%4.4x' % tag)
+      raise subcmd.TpmTestError(prefix + 'bad tag value 0x%4.4x' % tag)
     if size != len(data_blob):
-      raise TpmError(prefix + 'size mismatch: header %d, actual %d' %
-                     (size, len(data_blob)))
+      raise subcmd.TpmTestError(prefix + 'size mismatch: header %d, actual %d'
+                                % (size, len(data_blob)))
     if size > 4096:
-      raise TpmError(prefix + 'invalid size %d' % size)
+      raise subcmd.TpmTestError(prefix + 'invalid size %d' % size)
     if response_mode:
       return
     if cmd_code >= 0x11f and cmd_code <= 0x18f:
@@ -80,7 +77,7 @@ class TPM(object):
     if cmd_code == EXT_CMD:
       return  # This is an extension command
 
-    raise TpmError(prefix + 'invalid command code 0x%x' % cmd_code)
+    raise subcmd.TpmTestError(prefix + 'invalid command code 0x%x' % cmd_code)
 
   def command(self, cmd_data):
     # Verify command header
@@ -108,21 +105,22 @@ class TPM(object):
     Returns:
       the binary string of the response payload, if validation succeeded.
     Raises:
-      TpmError: in case there are any validation problems, the error message
-        describes the problem.
+      subcmd.TpmTestError: in case there are any validation problems, the
+        error message describes the problem.
     """
     header_size = struct.calcsize(self.HEADER_FMT)
     tag, size, cmd, subcmd = struct.unpack(self.HEADER_FMT,
                                            response[:header_size])
     if tag != 0x8001:
-      raise TpmError('Wrong response tag: %4.4x' % tag)
+      raise subcmd.TpmTestError('Wrong response tag: %4.4x' % tag)
     if cmd != EXT_CMD:
-      raise TpmError('Unexpected response command field: %8.8x' % cmd)
+      raise subcmd.TpmTestError('Unexpected response command field: %8.8x' %
+                                cmd)
     if subcmd != expected_subcmd:
-      raise TpmError('Unexpected response subcommand field: %2.2x' %
+      raise subcmd.TpmTestError('Unexpected response subcommand field: %2.2x' %
                      subcmd)
     if size != len(response):
-      raise TpmError('Size mismatch: header %d, actual %d' % (
+      raise subcmd.TpmTestError('Size mismatch: header %d, actual %d' % (
           size, len(response)))
     return response[header_size:]
 
@@ -139,10 +137,9 @@ if __name__ == '__main__':
     ecc_test.ecc_test(t)
     hash_test.hash_test(t)
     rsa_test.rsa_test(t)
-  except (TpmError, crypto_test.CryptoError, hash_test.HashError,
-          rsa_test.RSAError) as e:
-    print()
-    print('Error:', e)
+  except subcmd.TpmTestError as e:
+    exc_file, exc_line = traceback.extract_tb(sys.exc_traceback)[-1][:2]
+    print('\nError in %s:%s: ' % (os.path.basename(exc_file), exc_line), e)
     if debug_needed:
       traceback.print_exc()
     sys.exit(1)