diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 453036e37..abec3c89f 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -4,7 +4,7 @@ repos:
 - repo: https://github.com/pre-commit/pre-commit-hooks
   rev: v2.3.0
   hooks:
-    # - id: check-builtin-literals  # TODO: enable when fixed.
+    - id: check-builtin-literals
     - id: check-added-large-files
     - id: check-case-conflict
     - id: check-toml
diff --git a/src/pip/_internal/index.py b/src/pip/_internal/index.py
index 4db14eb1a..81bdd4ad5 100644
--- a/src/pip/_internal/index.py
+++ b/src/pip/_internal/index.py
@@ -34,7 +34,7 @@ from pip._internal.wheel import Wheel
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Any, FrozenSet, Iterable, List, Optional, Set, Text, Tuple,
+        FrozenSet, Iterable, List, Optional, Set, Text, Tuple, Union,
     )
     from pip._vendor.packaging.version import _BaseVersion
     from pip._internal.collector import LinkCollector
@@ -43,7 +43,7 @@ if MYPY_CHECK_RUNNING:
     from pip._internal.pep425tags import Pep425Tag
     from pip._internal.utils.hashes import Hashes
 
-    BuildTag = Tuple[Any, ...]  # either empty tuple or Tuple[int, str]
+    BuildTag = Union[Tuple[()], Tuple[int, str]]
     CandidateSortingKey = (
         Tuple[int, int, int, _BaseVersion, BuildTag, Optional[int]]
     )
@@ -511,7 +511,7 @@ class CandidateEvaluator(object):
         """
         valid_tags = self._supported_tags
         support_num = len(valid_tags)
-        build_tag = tuple()  # type: BuildTag
+        build_tag = ()  # type: BuildTag
         binary_preference = 0
         link = candidate.link
         if link.is_wheel:
diff --git a/src/pip/_internal/operations/check.py b/src/pip/_internal/operations/check.py
index 3bc9f8107..9f7fe6a7f 100644
--- a/src/pip/_internal/operations/check.py
+++ b/src/pip/_internal/operations/check.py
@@ -68,8 +68,8 @@ def check_package_set(package_set, should_ignore=None):
         def should_ignore(name):
             return False
 
-    missing = dict()
-    conflicting = dict()
+    missing = {}
+    conflicting = {}
 
     for package_name in package_set:
         # Info about dependencies of package_name
diff --git a/tests/conftest.py b/tests/conftest.py
index 5982ebf90..e29f03e59 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -181,10 +181,10 @@ def pip_src(tmpdir_factory):
             return to_ignore
 
         # Ignore all compiled files and egg-info.
-        ignored = list()
-        for pattern in ["__pycache__", "*.pyc", "pip.egg-info"]:
-            ignored.extend(fnmatch.filter(names, pattern))
-        return set(ignored)
+        ignored = set()
+        for pattern in ("__pycache__", "*.pyc", "pip.egg-info"):
+            ignored.update(fnmatch.filter(names, pattern))
+        return ignored
 
     pip_src = Path(str(tmpdir_factory.mktemp('pip_src'))).joinpath('pip_src')
     # Copy over our source tree so that each use is self contained