diff --git a/src/joserfc/_keys.py b/src/joserfc/_keys.py
index cbb5d26..e33ab7e 100644
--- a/src/joserfc/_keys.py
+++ b/src/joserfc/_keys.py
@@ -167,7 +167,13 @@ def import_key_set(cls, value: KeySetSerialization, parameters: KeyParameters |
         keys: list[Key] = []
 
         for data in value["keys"]:
-            keys.append(cls.registry_cls.import_key(data, parameters=parameters))
+            # RFC 7517, Section 5: ignore a key whose "kty" is not understood
+            # rather than failing the whole set (for example a post-quantum key
+            # published alongside classical ones).
+            try:
+                keys.append(cls.registry_cls.import_key(data, parameters=parameters))
+            except InvalidKeyTypeError:
+                continue
 
         if not keys:
             raise MissingKeyError("No keys to import")
diff --git a/tests/jwk/test_jwk_set.py b/tests/jwk/test_jwk_set.py
index 45f9e38..06c4bbc 100644
--- a/tests/jwk/test_jwk_set.py
+++ b/tests/jwk/test_jwk_set.py
@@ -11,6 +11,16 @@ class TestKeySet(TestCase):
     def test_import_empty_key_set(self):
         self.assertRaises(MissingKeyError, KeySet.import_key_set, {"keys": []})
 
+    def test_import_key_set_ignores_unknown_kty(self):
+        # RFC 7517 Section 5: a key with an unrecognised "kty" is ignored, not fatal.
+        jwks = {"keys": [
+            {"kty": "unknown", "alg": "X", "kid": "unknown"},
+            {"kty": "oct", "k": "MDEyMzQ1Njc4OWFiY2RlZg", "kid": "classical"},
+        ]}
+        key_set = KeySet.import_key_set(jwks)
+        self.assertEqual(len(key_set.keys), 1)
+        self.assertEqual(key_set.keys[0].kid, "classical")
+
     def test_generate_and_import_key_set(self):
         jwks1 = KeySet.generate_key_set("RSA", 2048)
         self.assertEqual(len(jwks1.keys), 4)