Tighten type checking of string values (#556)

In Python 3, these values will always be str.

2 files changed, 4 insertions, 4 deletions

diff --git a/jwt/api_jws.py b/jwt/api_jws.py
index e9a087c..17c49db 100644
--- a/jwt/api_jws.py
+++ b/jwt/api_jws.py
@@ -243,7 +243,7 @@ class PyJWS:
             self._validate_kid(headers["kid"])
 
     def _validate_kid(self, kid):
-        if not isinstance(kid, (bytes, str)):
+        if not isinstance(kid, str):
             raise InvalidTokenError("Key ID header parameter must be a string")
 
 
diff --git a/jwt/api_jwt.py b/jwt/api_jwt.py
index 7d11140..68597a8 100644
--- a/jwt/api_jwt.py
+++ b/jwt/api_jwt.py
@@ -188,14 +188,14 @@ class PyJWT(PyJWS):
 
         audience_claims = payload["aud"]
 
-        if isinstance(audience_claims, (bytes, str)):
+        if isinstance(audience_claims, str):
             audience_claims = [audience_claims]
         if not isinstance(audience_claims, list):
             raise InvalidAudienceError("Invalid claim format in token")
-        if any(not isinstance(c, (bytes, str)) for c in audience_claims):
+        if any(not isinstance(c, str) for c in audience_claims):
             raise InvalidAudienceError("Invalid claim format in token")
 
-        if isinstance(audience, (bytes, str)):
+        if isinstance(audience, str):
             audience = [audience]
 
         if not any(aud in audience_claims for aud in audience):