diff --git a/src/requests/_internal_utils.py b/src/requests/_internal_utils.py
index f2cf635e29..74684b1937 100644
--- a/src/requests/_internal_utils.py
+++ b/src/requests/_internal_utils.py
@@ -8,6 +8,7 @@
 import re
 
 from .compat import builtin_str
+from .compat import str as builtin_str
 
 _VALID_HEADER_NAME_RE_BYTE = re.compile(rb"^[^:\s][^:\r\n]*$")
 _VALID_HEADER_NAME_RE_STR = re.compile(r"^[^:\s][^:\r\n]*$")
@@ -27,12 +28,7 @@ def to_native_string(string, encoding="ascii"):
     that string in the native string type, encoding and decoding where
     necessary. This assumes ASCII unless told otherwise.
     """
-    if isinstance(string, builtin_str):
-        out = string
-    else:
-        out = string.decode(encoding)
-
-    return out
+    return string if isinstance(string, builtin_str) else string.decode(encoding)
 
 
 def unicode_is_ascii(u_string):
diff --git a/src/requests/auth.py b/src/requests/auth.py
index 4a7ce6dc14..3fda2c5306 100644
--- a/src/requests/auth.py
+++ b/src/requests/auth.py
@@ -14,7 +14,10 @@
 from base64 import b64encode
 
 from ._internal_utils import to_native_string
-from .compat import basestring, str, urlparse
+from .compat import basestring
+from .compat import str
+from .compat import str as builtin_str
+from .compat import urlparse
 from .cookies import extract_cookies_to_jar
 from .utils import parse_dict_header
 
@@ -25,13 +28,7 @@
 def _basic_auth_str(username, password):
     """Returns a Basic Auth string."""
 
-    # "I want us to put a big-ol' comment on top of it that
-    # says that this behaviour is dumb but we need to preserve
-    # it because people are relying on it."
-    #    - Lukasa
-    #
-    # These are here solely to maintain backwards compatibility
-    # for things like ints. This will be removed in 3.0.0.
+    # Maintain backwards compatibility
     if not isinstance(username, basestring):
         warnings.warn(
             "Non-string usernames will no longer be supported in Requests "
@@ -40,7 +37,7 @@ def _basic_auth_str(username, password):
             "problems.".format(username),
             category=DeprecationWarning,
         )
-        username = str(username)
+        username = builtin_str(username)
 
     if not isinstance(password, basestring):
         warnings.warn(
@@ -50,14 +47,11 @@ def _basic_auth_str(username, password):
             "problems.".format(type(password)),
             category=DeprecationWarning,
         )
-        password = str(password)
+        password = builtin_str(password)
     # -- End Removal --
 
-    if isinstance(username, str):
-        username = username.encode("latin1")
-
-    if isinstance(password, str):
-        password = password.encode("latin1")
+    username = username.encode("latin1") if isinstance(username, str) else username
+    password = password.encode("latin1") if isinstance(password, str) else password
 
     authstr = "Basic " + to_native_string(
         b64encode(b":".join((username, password))).strip()
diff --git a/src/requests/compat.py b/src/requests/compat.py
index 7f9d754350..2fbd02bec3 100644
--- a/src/requests/compat.py
+++ b/src/requests/compat.py
@@ -74,29 +74,14 @@ def _resolve_char_detection():
 from http import cookiejar as cookielib
 from http.cookies import Morsel
 from io import StringIO
-
 # --------------
 # Legacy Imports
 # --------------
-from urllib.parse import (
-    quote,
-    quote_plus,
-    unquote,
-    unquote_plus,
-    urldefrag,
-    urlencode,
-    urljoin,
-    urlparse,
-    urlsplit,
-    urlunparse,
-)
-from urllib.request import (
-    getproxies,
-    getproxies_environment,
-    parse_http_list,
-    proxy_bypass,
-    proxy_bypass_environment,
-)
+from urllib.parse import (quote, quote_plus, unquote, unquote_plus, urldefrag,
+                          urlencode, urljoin, urlparse, urlsplit, urlunparse)
+from urllib.request import (getproxies, getproxies_environment,
+                            parse_http_list, proxy_bypass,
+                            proxy_bypass_environment)
 
 builtin_str = str
 str = str