diff --git a/planetmint/backend/exceptions.py b/planetmint/backend/exceptions.py
index 2ab5ef6..cf22952 100644
--- a/planetmint/backend/exceptions.py
+++ b/planetmint/backend/exceptions.py
@@ -3,10 +3,10 @@
 # SPDX-License-Identifier: (Apache-2.0 AND CC-BY-4.0)
 # Code is Apache-2.0 and docs are CC-BY-4.0
 
-from planetmint.exceptions import BigchainDBError
+from planetmint.exceptions import PlanetmintError
 
 
-class BackendError(BigchainDBError):
+class BackendError(PlanetmintError):
     """Top level exception for any backend exception."""
 
 
diff --git a/planetmint/exceptions.py b/planetmint/exceptions.py
index 9e12b7c..624f1e9 100644
--- a/planetmint/exceptions.py
+++ b/planetmint/exceptions.py
@@ -4,9 +4,9 @@
 # Code is Apache-2.0 and docs are CC-BY-4.0
 
 
-class BigchainDBError(Exception):
+class PlanetmintError(Exception):
     """Base class for Planetmint exceptions."""
 
 
-class CriticalDoubleSpend(BigchainDBError):
+class CriticalDoubleSpend(PlanetmintError):
     """Data integrity error that requires attention"""
diff --git a/planetmint/lib.py b/planetmint/lib.py
index 3c37124..ceb8a0c 100644
--- a/planetmint/lib.py
+++ b/planetmint/lib.py
@@ -13,11 +13,7 @@ from uuid import uuid4
 
 import rapidjson
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    # NOTE: needed for Python < 3.6
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 import requests
 
diff --git a/planetmint/tendermint_utils.py b/planetmint/tendermint_utils.py
index 508a1be..ad7bb66 100644
--- a/planetmint/tendermint_utils.py
+++ b/planetmint/tendermint_utils.py
@@ -8,10 +8,7 @@ import hashlib
 import json
 from binascii import hexlify
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 
 def encode_transaction(value):
diff --git a/planetmint/transactions/common/crypto.py b/planetmint/transactions/common/crypto.py
index 0812018..968088d 100644
--- a/planetmint/transactions/common/crypto.py
+++ b/planetmint/transactions/common/crypto.py
@@ -5,12 +5,7 @@
 
 # Separate all crypto code so that we can easily test several implementations
 from collections import namedtuple
-
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
-
+from hashlib import sha3_256
 from cryptoconditions import crypto
 
 
diff --git a/planetmint/transactions/common/exceptions.py b/planetmint/transactions/common/exceptions.py
index ed0c307..780fe01 100644
--- a/planetmint/transactions/common/exceptions.py
+++ b/planetmint/transactions/common/exceptions.py
@@ -5,32 +5,32 @@
 
 """Custom exceptions used in the `planetmint` package.
 """
-from planetmint.exceptions import BigchainDBError
+from planetmint.exceptions import PlanetmintError
 
 
-class ConfigurationError(BigchainDBError):
+class ConfigurationError(PlanetmintError):
     """Raised when there is a problem with server configuration"""
 
 
-class DatabaseDoesNotExist(BigchainDBError):
+class DatabaseDoesNotExist(PlanetmintError):
     """Raised when trying to delete the database but the db is not there"""
 
 
-class StartupError(BigchainDBError):
+class StartupError(PlanetmintError):
     """Raised when there is an error starting up the system"""
 
 
-class CyclicBlockchainError(BigchainDBError):
+class CyclicBlockchainError(PlanetmintError):
     """Raised when there is a cycle in the blockchain"""
 
 
-class KeypairMismatchException(BigchainDBError):
+class KeypairMismatchException(PlanetmintError):
     """Raised if the private key(s) provided for signing don't match any of the
     current owner(s)
     """
 
 
-class OperationError(BigchainDBError):
+class OperationError(PlanetmintError):
     """Raised when an operation cannot go through"""
 
 
@@ -43,7 +43,7 @@ class OperationError(BigchainDBError):
 # especially for the purposes of testing.
 
 
-class ValidationError(BigchainDBError):
+class ValidationError(PlanetmintError):
     """Raised if there was an error in validation"""
 
 
diff --git a/planetmint/transactions/common/transaction.py b/planetmint/transactions/common/transaction.py
index 33f504c..48f2aaf 100644
--- a/planetmint/transactions/common/transaction.py
+++ b/planetmint/transactions/common/transaction.py
@@ -21,10 +21,7 @@ from cryptoconditions import Fulfillment, ThresholdSha256, Ed25519Sha256, Zenroo
 from cryptoconditions.exceptions import ParsingError, ASN1DecodeError, ASN1EncodeError
 from cid import is_cid
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 from planetmint.transactions.common.crypto import PrivateKey, hash_data
 from planetmint.transactions.common.exceptions import (
diff --git a/tests/common/test_transaction.py b/tests/common/test_transaction.py
index 5e81937..1c0f0e7 100644
--- a/tests/common/test_transaction.py
+++ b/tests/common/test_transaction.py
@@ -22,12 +22,8 @@ from cryptoconditions import Fulfillment
 from cryptoconditions import PreimageSha256
 from cryptoconditions import Ed25519Sha256
 from pytest import mark, raises
-from ipld import marshal, multihash
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 pytestmark = mark.bdb
 
diff --git a/tests/tendermint/test_lib.py b/tests/tendermint/test_lib.py
index c7e7077..7c1e04a 100644
--- a/tests/tendermint/test_lib.py
+++ b/tests/tendermint/test_lib.py
@@ -9,11 +9,7 @@ from unittest.mock import patch
 from planetmint.transactions.types.assets.create import Create
 from planetmint.transactions.types.assets.transfer import Transfer
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    # NOTE: needed for Python < 3.6
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 import pytest
 from pymongo import MongoClient
diff --git a/tests/tendermint/test_utils.py b/tests/tendermint/test_utils.py
index fe9dc62..c6cfd45 100644
--- a/tests/tendermint/test_utils.py
+++ b/tests/tendermint/test_utils.py
@@ -7,10 +7,7 @@ import base64
 import json
 from pytest import mark
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 
 def test_encode_decode_transaction(b):
diff --git a/tests/validation/test_transaction_structure.py b/tests/validation/test_transaction_structure.py
index 83ccef3..aa5df28 100644
--- a/tests/validation/test_transaction_structure.py
+++ b/tests/validation/test_transaction_structure.py
@@ -11,10 +11,7 @@ import json
 
 import pytest
 
-try:
-    import hashlib as sha3
-except ImportError:
-    import sha3
+import hashlib as sha3
 from unittest.mock import MagicMock
 
 from planetmint.transactions.common.exceptions import AmountError, SchemaValidationError, ThresholdTooDeep
diff --git a/tests/web/test_transactions.py b/tests/web/test_transactions.py
index b2fd3e0..6ea6aad 100644
--- a/tests/web/test_transactions.py
+++ b/tests/web/test_transactions.py
@@ -11,10 +11,7 @@ import pytest
 from cryptoconditions import Ed25519Sha256
 from ipld import multihash, marshal
 
-try:
-    from hashlib import sha3_256
-except ImportError:
-    from sha3 import sha3_256
+from hashlib import sha3_256
 
 from planetmint.transactions.common import crypto
 from planetmint.transactions.types.assets.create import Create