diff --git a/tests/primitives/utils.py b/tests/primitives/utils.py
index 8b32700..a3759b0 100644
--- a/tests/primitives/utils.py
+++ b/tests/primitives/utils.py
@@ -43,7 +43,7 @@
 
 
 def generate_hash_test(param_loader, path, file_names, hash_cls,
-                       only_if=lambda api: True, skip_message=None):
+                       only_if=None, skip_message=None):
     def test_hash(self):
         for api in _ALL_APIS:
             for file_name in file_names:
@@ -60,7 +60,7 @@
 
 
 def hash_test(api, hash_cls, params, only_if, skip_message):
-    if not only_if(api):
+    if only_if is not None and not only_if(api):
         pytest.skip(skip_message)
     msg = params[0]
     md = params[1]
@@ -70,7 +70,7 @@
 
 
 def generate_base_hash_test(hash_cls, digest_size, block_size,
-                            only_if=lambda api: True, skip_message=None):
+                            only_if=None, skip_message=None):
     def test_base_hash(self):
         for api in _ALL_APIS:
             yield (
@@ -87,7 +87,7 @@
 
 def base_hash_test(api, hash_cls, digest_size, block_size, only_if,
                    skip_message):
-    if not only_if(api):
+    if only_if is not None and not only_if(api):
         pytest.skip(skip_message)
     m = hash_cls(api=api)
     assert m.digest_size == digest_size
@@ -97,7 +97,7 @@
     assert m._ctx != m_copy._ctx
 
 
-def generate_long_string_hash_test(hash_factory, md, only_if=lambda api: True,
+def generate_long_string_hash_test(hash_factory, md, only_if=None,
                                    skip_message=None):
     def test_long_string_hash(self):
         for api in _ALL_APIS:
@@ -113,7 +113,7 @@
 
 
 def long_string_hash_test(api, hash_factory, md, only_if, skip_message):
-    if not only_if(api):
+    if only_if is not None and not only_if(api):
         pytest.skip(skip_message)
     m = hash_factory(api)
     m.update(b"a" * 1000000)
diff --git a/tests/test_utils.py b/tests/test_utils.py
index a9bb6a8..3fe9e57 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -269,6 +269,20 @@
     ]
 
 
+def test_load_cryptrec_vectors_invalid():
+    vector_data = textwrap.dedent("""
+    # Vectors taken from http://info.isl.ntt.co.jp/crypt/eng/camellia/
+    # Download is t_camelia.txt
+
+    # Camellia with 128-bit key
+
+    E No.001 : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+    """).splitlines()
+
+    with pytest.raises(ValueError):
+        load_cryptrec_vectors(vector_data)
+
+
 def test_load_cryptrec_vectors_from_file_encrypt():
     test_set = load_cryptrec_vectors_from_file(
         "Camellia/NTT/camellia-128-ecb.txt"
diff --git a/tests/utils.py b/tests/utils.py
index 03b780f..fa7cc68 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -90,6 +90,8 @@
                 "plaintext": pt,
                 "ciphertext": ct
             })
+        else:
+            raise ValueError("Invalid line in file '{}'".format(line))
     return cryptrec_list
 
 
diff --git a/tox.ini b/tox.ini
index 0a28af1..e72eb58 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,7 +8,7 @@
     pretend
 commands =
     coverage run --source=cryptography/,tests/ -m pytest
-    coverage report -m
+    coverage report -m --fail-under 100
 
 [testenv:docs]
 deps = sphinx