diff --git a/tests/test_cli.py b/tests/test_cli.py
index c58effd..bee82d8 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -3,6 +3,10 @@ import os
 
 import pytest
 
+from typing import (
+    Optional,
+)
+
 from click.testing import CliRunner
 
 from eth2deposit import deposit
@@ -11,7 +15,7 @@ from eth2deposit.utils.constants import DEFAULT_VALIDATOR_KEYS_FOLDER_NAME
 from eth2deposit.key_handling.keystore import Keystore
 
 
-def clean_key_folder(my_folder_path):
+def clean_key_folder(my_folder_path: str) -> None:
     validator_keys_folder_path = os.path.join(my_folder_path, DEFAULT_VALIDATOR_KEYS_FOLDER_NAME)
     if not os.path.exists(validator_keys_folder_path):
         return
@@ -23,9 +27,9 @@ def clean_key_folder(my_folder_path):
     os.rmdir(my_folder_path)
 
 
-def test_deposit(monkeypatch):
+def test_deposit(monkeypatch) -> None:
     # monkeypatch get_mnemonic
-    def get_mnemonic(language, words_path, entropy=None):
+    def get_mnemonic(language: str, words_path: str, entropy: Optional[bytes]=None) -> str:
         return "fakephrase"
 
     monkeypatch.setattr(deposit, "get_mnemonic", get_mnemonic)
@@ -47,7 +51,7 @@ def test_deposit(monkeypatch):
     validator_keys_folder_path = os.path.join(my_folder_path, DEFAULT_VALIDATOR_KEYS_FOLDER_NAME)
     _, _, key_files = next(os.walk(validator_keys_folder_path))
 
-    def get_uuid(key_file):
+    def get_uuid(key_file: str) -> str:
         keystore = Keystore.from_json(key_file)
         return keystore.uuid
 
@@ -63,7 +67,7 @@ def test_deposit(monkeypatch):
 
 
 @pytest.mark.asyncio
-async def test_script():
+async def test_script() -> None:
     my_folder_path = os.path.join(os.getcwd(), 'TESTING_TEMP_FOLDER')
     if not os.path.exists(my_folder_path):
         os.mkdir(my_folder_path)
diff --git a/tests/test_key_handling/test_key_derivation/test_mnemonic.py b/tests/test_key_handling/test_key_derivation/test_mnemonic.py
index a3b254a..d374675 100644
--- a/tests/test_key_handling/test_key_derivation/test_mnemonic.py
+++ b/tests/test_key_handling/test_key_derivation/test_mnemonic.py
@@ -1,6 +1,9 @@
 import os
 import pytest
 import json
+from typing import (
+    Sequence,
+)
 
 from eth2deposit.key_handling.key_derivation.mnemonic import (
     get_seed,
@@ -17,14 +20,13 @@ with open(test_vector_filefolder, 'r', encoding='utf-8') as f:
 
 
 @pytest.mark.parametrize(
-    'language,language_test_vectors',
-    [(a, b) for a, b in test_vectors.items()]
+    'language,test',
+    [(language, test) for language, language_test_vectors in test_vectors.items() for test in language_test_vectors]
 )
-def test_bip39(language, language_test_vectors):
-    for test in language_test_vectors:
-        test_entropy = bytes.fromhex(test[0])
-        test_mnemonic = test[1]
-        test_seed = bytes.fromhex(test[2])
+def test_bip39(language: str, test: Sequence[str]) -> None:
+    test_entropy = bytes.fromhex(test[0])
+    test_mnemonic = test[1]
+    test_seed = bytes.fromhex(test[2])
 
-        assert get_mnemonic(language=language, words_path=WORD_LISTS_PATH, entropy=test_entropy) == test_mnemonic
-        assert get_seed(mnemonic=test_mnemonic, password='TREZOR') == test_seed
+    assert get_mnemonic(language=language, words_path=WORD_LISTS_PATH, entropy=test_entropy) == test_mnemonic
+    assert get_seed(mnemonic=test_mnemonic, password='TREZOR') == test_seed
diff --git a/tests/test_key_handling/test_key_derivation/test_path.py b/tests/test_key_handling/test_key_derivation/test_path.py
index 8443e9f..11deedc 100644
--- a/tests/test_key_handling/test_key_derivation/test_path.py
+++ b/tests/test_key_handling/test_key_derivation/test_path.py
@@ -1,5 +1,6 @@
 import os
 import json
+import pytest
 
 from eth2deposit.key_handling.key_derivation.tree import (
     _flip_bits_256,
@@ -15,15 +16,23 @@ from eth2deposit.key_handling.key_derivation.path import (
 test_vector_filefolder = os.path.join(os.getcwd(), 'tests', 'test_key_handling', 'test_key_derivation',
                                       'test_vectors', 'tree_kdf_intermediate.json')
 with open(test_vector_filefolder, 'r') as f:
-    test_vector = json.load(f)
+    test_vector_dict = json.load(f)
 
 
-def test_flip_bits_256() -> None:
+@pytest.mark.parametrize(
+    'test_vector',
+    [test_vector_dict]
+)
+def test_flip_bits_256(test_vector) -> None:
     test_vector_int = int(test_vector['seed'][:64], 16)  # 64 comes from string chars containing .5 bytes
     assert test_vector_int & _flip_bits_256(test_vector_int) == 0
 
 
-def test_IKM_to_lamport_SK() -> None:
+@pytest.mark.parametrize(
+    'test_vector',
+    [test_vector_dict]
+)
+def test_IKM_to_lamport_SK(test_vector) -> None:
     test_vector_lamport_0 = [bytes.fromhex(x) for x in test_vector['lamport_0']]
     test_vector_lamport_1 = [bytes.fromhex(x) for x in test_vector['lamport_1']]
     salt = test_vector['child_index'].to_bytes(4, 'big')
@@ -35,21 +44,33 @@ def test_IKM_to_lamport_SK() -> None:
     assert test_vector_lamport_1 == lamport_1
 
 
-def test_parent_SK_to_lamport_PK() -> None:
+@pytest.mark.parametrize(
+    'test_vector',
+    [test_vector_dict]
+)
+def test_parent_SK_to_lamport_PK(test_vector) -> None:
     parent_SK = test_vector['master_SK']
     index = test_vector['child_index']
     lamport_PK = bytes.fromhex(test_vector['compressed_lamport_PK'])
     assert lamport_PK == _parent_SK_to_lamport_PK(parent_SK=parent_SK, index=index)
 
 
-def test_HKDF_mod_r() -> None:
+@pytest.mark.parametrize(
+    'test_vector',
+    [test_vector_dict]
+)
+def test_HKDF_mod_r(test_vector) -> None:
     test_0 = (bytes.fromhex(test_vector['seed']), test_vector['master_SK'])
     test_1 = (bytes.fromhex(test_vector['compressed_lamport_PK']), test_vector['child_SK'])
     for test in (test_0, test_1):
         assert _HKDF_mod_r(IKM=test[0]) == test[1]
 
 
-def test_mnemonic_and_path_to_key() -> None:
+@pytest.mark.parametrize(
+    'test_vector',
+    [test_vector_dict]
+)
+def test_mnemonic_and_path_to_key(test_vector) -> None:
     mnemonic = test_vector['mnemonic']
     password = test_vector['password']
     path = test_vector['path']
diff --git a/tests/test_key_handling/test_key_derivation/test_tree.py b/tests/test_key_handling/test_key_derivation/test_tree.py
index d6e735d..70c0f9e 100644
--- a/tests/test_key_handling/test_key_derivation/test_tree.py
+++ b/tests/test_key_handling/test_key_derivation/test_tree.py
@@ -57,8 +57,3 @@ def test_derive_child_SK(test) -> None:
     index = test['child_index']
     child_SK = test['child_SK']
     assert derive_child_SK(parent_SK=parent_SK, index=index) == child_SK
-    for test in test_vectors:
-        parent_SK = test['master_SK']
-        index = test['child_index']
-        child_SK = test['child_SK']
-        assert derive_child_SK(parent_SK=parent_SK, index=index) == child_SK
diff --git a/tests/test_key_handling/test_keystore.py b/tests/test_key_handling/test_keystore.py
index 5f321c1..462e232 100644
--- a/tests/test_key_handling/test_keystore.py
+++ b/tests/test_key_handling/test_keystore.py
@@ -15,14 +15,14 @@ _, _, test_vector_files = next(os.walk(test_vector_folder))  # type: ignore
 test_vector_keystores = [Keystore.from_json(os.path.join(test_vector_folder, f)) for f in test_vector_files]
 
 
-def test_json_serialization():
+def test_json_serialization() -> None:
     for keystore, keystore_json_file in zip(test_vector_keystores, test_vector_files):
         keystore_json_path = os.path.join(test_vector_folder, keystore_json_file)
         with open(keystore_json_path) as f:
             assert json.loads(keystore.as_json()) == json.load(f)
 
 
-def test_encrypt_decrypt_test_vectors():
+def test_encrypt_decrypt_test_vectors() -> None:
     for tv in test_vector_keystores:
         aes_iv = tv.crypto.cipher.params['iv']
         kdf_salt = tv.crypto.kdf.params['salt']
@@ -35,7 +35,7 @@ def test_encrypt_decrypt_test_vectors():
         assert generated_keystore.decrypt(test_vector_password) == test_vector_secret
 
 
-def test_generated_keystores():
+def test_generated_keystores() -> None:
     for tv in test_vector_keystores:
         aes_iv = tv.crypto.cipher.params['iv']
         kdf_salt = tv.crypto.kdf.params['salt']
@@ -48,11 +48,11 @@ def test_generated_keystores():
         assert generated_keystore.crypto == tv.crypto
 
 
-def test_encrypt_decrypt_pbkdf2_random_iv():
+def test_encrypt_decrypt_pbkdf2_random_iv() -> None:
     generated_keystore = Pbkdf2Keystore.encrypt(secret=test_vector_secret, password=test_vector_password)
     assert generated_keystore.decrypt(test_vector_password) == test_vector_secret
 
 
-def test_encrypt_decrypt_scrypt_random_iv():
+def test_encrypt_decrypt_scrypt_random_iv() -> None:
     generated_keystore = ScryptKeystore.encrypt(secret=test_vector_secret, password=test_vector_password)
     assert generated_keystore.decrypt(test_vector_password) == test_vector_secret