diff --git a/.python-version b/.python-version
new file mode 100644
index 0000000..cc1923a
--- /dev/null
+++ b/.python-version
@@ -0,0 +1 @@
+3.8
diff --git a/rust/cargo_config.py b/rust/cargo_config.py
index 446c45a..fadff2e 100644
--- a/rust/cargo_config.py
+++ b/rust/cargo_config.py
@@ -410,8 +410,8 @@ def _toolchain_list(self):
         # https://static.rust-lang.org/dist/index.html
         # (See https://github.com/rust-lang-nursery/rustup.rs/issues/215)
         shorthands = []
-        channels = ['nightly', 'beta', 'stable', '\d\.\d{1,2}\.\d']
-        pattern = '(%s)(?:-(\d{4}-\d{2}-\d{2}))?(?:-(.*))' % '|'.join(channels)
+        channels = ['nightly', 'beta', 'stable', r'\d\.\d{1,2}\.\d']
+        pattern = r'(%s)(?:-(\d{4}-\d{2}-\d{2}))?(?:-(.*))' % '|'.join(channels)
         for toolchain in output:
             m = re.match(pattern, toolchain)
             # Should always match.
diff --git a/rust/cargo_settings.py b/rust/cargo_settings.py
index c2177c5..4f65d41 100644
--- a/rust/cargo_settings.py
+++ b/rust/cargo_settings.py
@@ -48,7 +48,7 @@
         'allows_release': True,
         'allows_features': True,
         'allows_json': True,
-        'json_stop_pattern': '^\s*Running ',
+        'json_stop_pattern': r'^\s*Running ',
     },
     'check': {
         'name': 'Check',