diff --git a/bootstrap/bootstrap.py b/bootstrap/bootstrap.py
index 23739df5b..0315c1342 100644
--- a/bootstrap/bootstrap.py
+++ b/bootstrap/bootstrap.py
@@ -211,7 +211,7 @@ def get_os_release_variable(key):
 class ProgressPageRequestHandler(SimpleHTTPRequestHandler):
     def do_GET(self):
         if self.path == "/logs":
-            with open("/opt/tljh/installer.log", "r") as log_file:
+            with open("/opt/tljh/installer.log") as log_file:
                 logs = log_file.read()
 
             self.send_response(200)
diff --git a/integration-tests/test_extensions.py b/integration-tests/test_extensions.py
index 973f784f4..13b305ada 100644
--- a/integration-tests/test_extensions.py
+++ b/integration-tests/test_extensions.py
@@ -38,7 +38,7 @@ def test_nbextensions():
     ]
 
     for e in extensions:
-        assert '{} \x1b[32m enabled \x1b[0m'.format(e) in proc.stdout.decode()
+        assert f'{e} \x1b[32m enabled \x1b[0m' in proc.stdout.decode()
 
     # Ensure we have 'OK' messages in our stdout, to make sure everything is importable
     assert proc.stderr.decode() == '      - Validating: \x1b[32mOK\x1b[0m\n' * len(extensions)
diff --git a/tests/test_conda.py b/tests/test_conda.py
index 539e6469f..a4db0134d 100644
--- a/tests/test_conda.py
+++ b/tests/test_conda.py
@@ -59,7 +59,7 @@ def test_ensure_pip_requirements(prefix):
     conda.ensure_conda_packages(prefix, ['pip'])
     with tempfile.NamedTemporaryFile() as f:
         # Sample small package to test
-        f.write('there'.encode())
+        f.write(b'there')
         f.flush()
         conda.ensure_pip_requirements(prefix, f.name)
     subprocess.check_call([
diff --git a/tests/test_installer.py b/tests/test_installer.py
index ca13cc5be..361d394c1 100644
--- a/tests/test_installer.py
+++ b/tests/test_installer.py
@@ -31,7 +31,7 @@ def test_ensure_admins(tljh_dir, admins, expected_config):
 	installer.ensure_admins(admins)
 
 	config_path = installer.CONFIG_FILE
-	with open(config_path, 'r') as f:
+	with open(config_path) as f:
 	    config = yaml.load(f)
 
 	# verify the list was flattened
diff --git a/tljh/conda.py b/tljh/conda.py
index 6827c4778..7ef409907 100644
--- a/tljh/conda.py
+++ b/tljh/conda.py
@@ -72,7 +72,7 @@ def fix_permissions(prefix):
     Run after each install command.
     """
     utils.run_subprocess(
-        ["chown", "-R", "{}:{}".format(os.getuid(), os.getgid()), prefix]
+        ["chown", "-R", f"{os.getuid()}:{os.getgid()}", prefix]
     )
     utils.run_subprocess(["chmod", "-R", "o-w", prefix])
 
diff --git a/tljh/configurer.py b/tljh/configurer.py
index 02235a9f0..36bb69dd7 100644
--- a/tljh/configurer.py
+++ b/tljh/configurer.py
@@ -121,7 +121,7 @@ def load_traefik_api_credentials():
     proxy_secret_path = os.path.join(STATE_DIR, 'traefik-api.secret')
     if not os.path.exists(proxy_secret_path):
         return {}
-    with open(proxy_secret_path, 'r') as f:
+    with open(proxy_secret_path) as f:
         password = f.read()
     return {
         'traefik_api': {
diff --git a/tljh/installer.py b/tljh/installer.py
index ad306dac9..3bb4e8437 100644
--- a/tljh/installer.py
+++ b/tljh/installer.py
@@ -225,7 +225,7 @@ def ensure_admins(admin_password_list):
     logger.info("Setting up admin users")
     config_path = CONFIG_FILE
     if os.path.exists(config_path):
-        with open(config_path, 'r') as f:
+        with open(config_path) as f:
             config = yaml.load(f)
     else:
         config = {}
@@ -261,7 +261,7 @@ def ensure_jupyterhub_running(times=20):
 
     for i in range(times):
         try:
-            logger.info('Waiting for JupyterHub to come up ({}/{} tries)'.format(i + 1, times))
+            logger.info(f'Waiting for JupyterHub to come up ({i + 1}/{times} tries)')
             # Because we don't care at this level that SSL is valid, we can suppress
             # InsecureRequestWarning for this request.
             with warnings.catch_warnings():
@@ -283,7 +283,7 @@ def ensure_jupyterhub_running(times=20):
             # Everything else should immediately abort
             raise
 
-    raise Exception("Installation failed: JupyterHub did not start in {}s".format(times))
+    raise Exception(f"Installation failed: JupyterHub did not start in {times}s")
 
 
 def ensure_symlinks(prefix):
@@ -388,7 +388,7 @@ def ensure_config_yaml(plugin_manager):
     migrator.migrate_config_files()
 
     if os.path.exists(CONFIG_FILE):
-        with open(CONFIG_FILE, 'r') as f:
+        with open(CONFIG_FILE) as f:
             config = yaml.load(f)
     else:
         config = {}
diff --git a/tljh/traefik.py b/tljh/traefik.py
index 997cf00a9..4c3151f4e 100644
--- a/tljh/traefik.py
+++ b/tljh/traefik.py
@@ -69,7 +69,7 @@ def ensure_traefik_binary(prefix):
     # verify that we got what we expected
     checksum = checksum_file(traefik_bin)
     if checksum != checksums[plat]:
-        raise IOError(f"Checksum failed {traefik_bin}: {checksum} != {checksums[plat]}")
+        raise OSError(f"Checksum failed {traefik_bin}: {checksum} != {checksums[plat]}")
 
 
 def compute_basic_auth(username, password):
diff --git a/tljh/user.py b/tljh/user.py
index d4daf1fc7..edd2d90a4 100644
--- a/tljh/user.py
+++ b/tljh/user.py
@@ -34,7 +34,7 @@ def ensure_user(username):
     subprocess.check_call([
         'chmod',
         'o-rwx',
-        expanduser('~{username}'.format(username=username))
+        expanduser(f'~{username}')
     ])
 
     pm = get_plugin_manager()