diff --git a/noise/noise_protocol.py b/noise/noise_protocol.py
index 5d722d3..0aedf94 100644
--- a/noise/noise_protocol.py
+++ b/noise/noise_protocol.py
@@ -59,7 +59,7 @@ class NoiseProtocol(object):
     def _parse_protocol_name(self) -> Tuple[dict, list]:
         unpacked = self.name.split('_')
         if unpacked[0] != 'Noise':
-            raise ValueError(f'Noise Protocol name shall begin with Noise! Provided: {self.name}')
+            raise ValueError('Noise Protocol name shall begin with Noise! Provided: {}'.format(self.name))
 
         # Extract pattern name and pattern modifiers
         pattern = ''
@@ -85,7 +85,8 @@ class NoiseProtocol(object):
         for key, map_dict in self.methods.items():
             func = map_dict.get(data[key])
             if not func:
-                raise ValueError(f'Unknown {key} in Noise Protocol name, given {data[key]}, known {" ".join(map_dict)}')
+                raise ValueError('Unknown {} in Noise Protocol name, given {}, known {}'.format(
+                    key, data[key], " ".join(map_dict)))
             mapped_data[key] = func
 
         return mapped_data, modifiers
diff --git a/noise/patterns.py b/noise/patterns.py
index 47c3d18..4c6de8e 100644
--- a/noise/patterns.py
+++ b/noise/patterns.py
@@ -34,10 +34,10 @@ class Pattern(object):
                 try:
                     index = int(modifier.replace('psk', '', 1))
                 except ValueError:
-                    raise ValueError(f'Improper psk modifier {modifier}')
+                    raise ValueError('Improper psk modifier {}'.format(modifier))
 
                 if index // 2 > len(self.tokens):
-                    raise ValueError(f'Modifier {modifier} cannot be applied - pattern has not enough messages')
+                    raise ValueError('Modifier {} cannot be applied - pattern has not enough messages'.format(modifier))
 
                 # Add TOKEN_PSK in the correct place in the correct message
                 if index % 2 == 0:
@@ -49,7 +49,7 @@ class Pattern(object):
                 raise NotImplementedError  # TODO implement
 
             else:
-                raise ValueError(f'Unknown pattern modifier {modifier}')
+                raise ValueError('Unknown pattern modifier {}'.format(modifier))
 
 
 # One-way patterns
diff --git a/tests/test_vectors.py b/tests/test_vectors.py
index f325efa..ee99b26 100644
--- a/tests/test_vectors.py
+++ b/tests/test_vectors.py
@@ -16,7 +16,7 @@ def prepare_test_vectors():
     vectors = []
     for path in vector_files:
         with open(os.path.join(os.path.dirname(__file__), path)) as fd:
-            logging.info(f'Reading vectors from file {path}')
+            logging.info('Reading vectors from file {}'.format(path))
             vectors.extend(json.load(fd))
     return vectors
 
@@ -27,7 +27,7 @@ def vector(request):
 
 
 def test_vector(vector):
-    logging.info(f"Testing vector {vector['protocol_name']}")
+    logging.info('Testing vector {}'.format(vector['protocol_name']))
     init_protocol = NoiseProtocol(vector['protocol_name'])
     resp_protocol = NoiseProtocol(vector['protocol_name'])
     initiator = HandshakeState.initialize(noise_protocol=init_protocol, handshake_pattern=init_protocol.pattern,