diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 7603cd9b9b..c12911e6ec 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -22,7 +22,7 @@ repos:
           - flake8-debugger
           - flake8-string-format
     repo: https://gitlab.com/pycqa/flake8
-    rev: 3.7.9
+    rev: 3.8.3
   - repo: local
     hooks:
     - id: pylint
diff --git a/dvc/repo/plots/data.py b/dvc/repo/plots/data.py
index 9ff23ccf90..91eed9abbd 100644
--- a/dvc/repo/plots/data.py
+++ b/dvc/repo/plots/data.py
@@ -114,10 +114,12 @@ def _find_data(data, fields=None, **kwargs):
         # just look for first list of dicts
         fields = set()
 
-    for l in _lists(data):
-        if all(isinstance(dp, dict) for dp in l):
-            if set(first(l).keys()) & fields == fields:
-                return l
+    for lst in _lists(data):
+        if (
+            all(isinstance(dp, dict) for dp in lst)
+            and set(first(lst).keys()) & fields == fields
+        ):
+            return lst
     raise PlotDataStructureError()
 
 
diff --git a/setup.py b/setup.py
index 300b5a23bc..687f7353c1 100644
--- a/setup.py
+++ b/setup.py
@@ -119,7 +119,7 @@ def run(self):
     "google-compute-engine==2.8.13",
     "Pygments",  # required by collective.checkdocs,
     "collective.checkdocs",
-    "flake8==3.7.9",
+    "flake8==3.8.3",
     "psutil",
     "flake8-docstrings",
     "pydocstyle<4.0",
diff --git a/tests/remotes/__init__.py b/tests/remotes/__init__.py
index 6a5b80166e..4cd648f7ed 100644
--- a/tests/remotes/__init__.py
+++ b/tests/remotes/__init__.py
@@ -9,14 +9,6 @@
 from .oss import OSS, TEST_OSS_REPO_BUCKET, oss, oss_server  # noqa: F401
 from .s3 import S3, TEST_AWS_REPO_BUCKET, real_s3, s3  # noqa: F401
 
-TEST_REMOTE = "upstream"
-TEST_CONFIG = {
-    "cache": {},
-    "core": {"remote": TEST_REMOTE},
-    "remote": {TEST_REMOTE: {"url": ""}},
-}
-
-
 from .gdrive import (  # noqa: F401; noqa: F401
     TEST_GDRIVE_REPO_BUCKET,
     GDrive,
@@ -35,6 +27,13 @@
     ssh_server,
 )
 
+TEST_REMOTE = "upstream"
+TEST_CONFIG = {
+    "cache": {},
+    "core": {"remote": TEST_REMOTE},
+    "remote": {TEST_REMOTE: {"url": ""}},
+}
+
 
 @pytest.fixture(scope="session")
 def docker():