diff --git a/Pipfile b/Pipfile
index deeedbff..f98fcf46 100644
--- a/Pipfile
+++ b/Pipfile
@@ -24,6 +24,9 @@ twine = "*"
 anaconda-client = "*"
 pipfile = "*"
 wheel = "*"
+xxhash = "*"
+aiohttp = "*"
+async-timeout = "*"
 
 [requires]
 python_version = "3.8"
diff --git a/mocket/compat.py b/mocket/compat.py
index 5b5f017e..8165d7c2 100644
--- a/mocket/compat.py
+++ b/mocket/compat.py
@@ -2,28 +2,20 @@
 import os
 import shlex
 
-encoding = os.getenv("MOCKET_ENCODING", "utf-8")
+ENCODING = os.getenv("MOCKET_ENCODING", "utf-8")
 
 text_type = str
 byte_type = bytes
 basestring = (str,)
 
-FileNotFoundError = FileNotFoundError
-BlockingIOError = BlockingIOError
 
-try:
-    from json.decoder import JSONDecodeError
-except ImportError:
-    JSONDecodeError = ValueError
-
-
-def encode_to_bytes(s, encoding=encoding):
+def encode_to_bytes(s, encoding=ENCODING):
     if isinstance(s, text_type):
         s = s.encode(encoding)
     return byte_type(s)
 
 
-def decode_from_bytes(s, encoding=encoding):
+def decode_from_bytes(s, encoding=ENCODING):
     if isinstance(s, byte_type):
         s = codecs.decode(s, encoding, "ignore")
     return text_type(s)
diff --git a/mocket/mocket.py b/mocket/mocket.py
index c4e3cafe..d8b1ab93 100644
--- a/mocket/mocket.py
+++ b/mocket/mocket.py
@@ -9,6 +9,7 @@
 import socket
 import ssl
 from datetime import datetime, timedelta
+from json.decoder import JSONDecodeError
 
 import decorator
 import urllib3
@@ -16,9 +17,6 @@
 from urllib3.util.ssl_ import wrap_socket as urllib3_wrap_socket
 
 from .compat import (
-    BlockingIOError,
-    FileNotFoundError,
-    JSONDecodeError,
     basestring,
     byte_type,
     decode_from_bytes,
diff --git a/run_tests.py b/run_tests.py
index 8cfcfd64..61420451 100644
--- a/run_tests.py
+++ b/run_tests.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-import os
 import sys
 
 
@@ -11,24 +10,10 @@ def main(args=None):
 
     major, minor = sys.version_info[:2]
 
-    python35 = False
-
-    extras = ["xxhash"]
-
-    # aiohttp available on Python >=3.5
-    if major == 3 and minor >= 5:
-        python35 = True
-
-        extras += ["aiohttp", "async_timeout"]
-
-    os.system("pipenv run pip install {}".format(" ".join(extras)))
-
     if not any(a for a in args[1:] if not a.startswith("-")):
         args.append("tests/main")
         args.append("mocket")
-
-        if python35:
-            args.append("tests/tests35")
+        args.append("tests/tests35")
 
         if major == 3 and minor >= 8:
             args.append("tests/tests38")