diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 7de2532f6d..47380e103d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -27,8 +27,20 @@ repos:
         files: "gym-unity/.*"
         args: [--ignore-missing-imports, --disallow-incomplete-defs]
 
+-   repo: https://gitlab.com/pycqa/flake8
+    rev: 3.8.1
+    hooks:
+    -   id: flake8
+        exclude: >
+            (?x)^(
+                .*_pb2.py|
+                .*_pb2_grpc.py
+            )$
+        # flake8-tidy-imports is used for banned-modules, not actually tidying
+        additional_dependencies: [flake8-comprehensions==3.2.2, flake8-tidy-imports==4.1.0, flake8-bugbear==20.1.4]
+
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.4.0
+    rev: v2.5.0
     hooks:
     -   id: mixed-line-ending
         exclude: >
@@ -38,14 +50,7 @@ repos:
                 .*.meta
             )$
         args: [--fix=lf]
-    -   id: flake8
-        exclude: >
-            (?x)^(
-                .*_pb2.py|
-                .*_pb2_grpc.py
-            )$
-        # flake8-tidy-imports is used for banned-modules, not actually tidying
-        additional_dependencies: [flake8-comprehensions==3.1.4, flake8-tidy-imports==4.0.0, flake8-bugbear==20.1.2]
+
     -   id: trailing-whitespace
         name: trailing-whitespace-markdown
         types: [markdown]
diff --git a/ml-agents/mlagents/trainers/ppo/trainer.py b/ml-agents/mlagents/trainers/ppo/trainer.py
index 6b2f81b9f8..6cbc47a297 100644
--- a/ml-agents/mlagents/trainers/ppo/trainer.py
+++ b/ml-agents/mlagents/trainers/ppo/trainer.py
@@ -203,9 +203,9 @@ def _update_policy(self):
             self.update_buffer.shuffle(sequence_length=self.policy.sequence_length)
             buffer = self.update_buffer
             max_num_batch = buffer_length // batch_size
-            for l in range(0, max_num_batch * batch_size, batch_size):
+            for i in range(0, max_num_batch * batch_size, batch_size):
                 update_stats = self.optimizer.update(
-                    buffer.make_mini_batch(l, l + batch_size), n_sequences
+                    buffer.make_mini_batch(i, i + batch_size), n_sequences
                 )
                 for stat_name, value in update_stats.items():
                     batch_update_stats[stat_name].append(value)
diff --git a/ml-agents/mlagents/trainers/subprocess_env_manager.py b/ml-agents/mlagents/trainers/subprocess_env_manager.py
index badff20104..0687cbdf14 100644
--- a/ml-agents/mlagents/trainers/subprocess_env_manager.py
+++ b/ml-agents/mlagents/trainers/subprocess_env_manager.py
@@ -301,7 +301,7 @@ def external_brains(self) -> Dict[BehaviorName, BrainParameters]:
         return self.env_workers[0].recv().payload
 
     def close(self) -> None:
-        logger.debug(f"SubprocessEnvManager closing.")
+        logger.debug("SubprocessEnvManager closing.")
         self.step_queue.close()
         self.step_queue.join_thread()
         for env_worker in self.env_workers:
diff --git a/ml-agents/tests/yamato/check_coverage_percent.py b/ml-agents/tests/yamato/check_coverage_percent.py
index a4b10105e7..e3f2f11f76 100644
--- a/ml-agents/tests/yamato/check_coverage_percent.py
+++ b/ml-agents/tests/yamato/check_coverage_percent.py
@@ -25,9 +25,9 @@ def check_coverage(root_dir, min_percentage):
         # Rather than try to parse the XML, just look for a line of the form
         # <Linecoverage>73.9</Linecoverage>
         lines = f.readlines()
-        for l in lines:
-            if "Linecoverage" in l:
-                pct = l.replace("<Linecoverage>", "").replace("</Linecoverage>", "")
+        for line in lines:
+            if "Linecoverage" in line:
+                pct = line.replace("<Linecoverage>", "").replace("</Linecoverage>", "")
                 pct = float(pct)
                 if pct < min_percentage:
                     print(
diff --git a/ml-agents/tests/yamato/yamato_utils.py b/ml-agents/tests/yamato/yamato_utils.py
index 7939836ff1..399ede176d 100644
--- a/ml-agents/tests/yamato/yamato_utils.py
+++ b/ml-agents/tests/yamato/yamato_utils.py
@@ -149,7 +149,7 @@ def undo_git_checkout():
     subprocess.check_call("git reset HEAD .", shell=True)
     subprocess.check_call("git checkout -- .", shell=True)
     # Ensure the cache isn't polluted with old compiled assemblies.
-    subprocess.check_call(f"rm -rf Project/Library", shell=True)
+    subprocess.check_call("rm -rf Project/Library", shell=True)
 
 
 def override_config_file(src_path, dest_path, **kwargs):
diff --git a/utils/validate_versions.py b/utils/validate_versions.py
index 4833387402..6d41ea33fa 100755
--- a/utils/validate_versions.py
+++ b/utils/validate_versions.py
@@ -39,9 +39,9 @@ def _escape_non_none(s: Optional[str]) -> str:
 
 def extract_version_string(filename):
     with open(filename) as f:
-        for l in f.readlines():
-            if l.startswith(VERSION_LINE_START):
-                return l.replace(VERSION_LINE_START, "").strip()
+        for line in f.readlines():
+            if line.startswith(VERSION_LINE_START):
+                return line.replace(VERSION_LINE_START, "").strip()
     return None