diff --git a/Makefile b/Makefile
index 019b0b9..5e5031e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 SHELL=/bin/bash
 
 lint:
-	ruff http_message_signatures
+	ruff check http_message_signatures
 	mypy --check-untyped-defs http_message_signatures
 
 test: lint
diff --git a/http_message_signatures/_algorithms.py b/http_message_signatures/_algorithms.py
index d6d31e1..dcccebc 100644
--- a/http_message_signatures/_algorithms.py
+++ b/http_message_signatures/_algorithms.py
@@ -91,9 +91,9 @@ def __init__(self, public_key=None, private_key=None, password=None):
             raise HTTPMessageSignaturesException("Unexpected public key type")
         if self.private_key and not isinstance(self.private_key, ec.EllipticCurvePrivateKey):
             raise HTTPMessageSignaturesException("Unexpected private key type")
-        if self.public_key and type(self.public_key.curve) != ec.SECP256R1:
+        if self.public_key and not isinstance(self.public_key.curve, ec.SECP256R1):
             raise HTTPMessageSignaturesException("Unexpected elliptic curve type in public key")
-        if self.private_key and type(self.private_key.curve) != ec.SECP256R1:
+        if self.private_key and not isinstance(self.private_key.curve, ec.SECP256R1):
             raise HTTPMessageSignaturesException("Unexpected elliptic curve type in private key")
         self.signature_algorithm = ec.ECDSA(hashes.SHA256())