diff --git a/binapy/binapy.py b/binapy/binapy.py
index 8f83961..88c479f 100644
--- a/binapy/binapy.py
+++ b/binapy/binapy.py
@@ -4,6 +4,7 @@
 
 import re
 import secrets
+from contextlib import suppress
 from functools import wraps
 from typing import (
     Any,
@@ -117,13 +118,13 @@ def re_match(self, pattern: str, encoding: str = "ascii") -> str:
             the decoded, matching `str`
 
         Raises:
-            ValueError: if the decoded str doesn't match `pattern`
+            ValueError: if the decoded str does not match `pattern`
 
         """
         res = self.decode(encoding)
         if re.match(pattern, res):
             return res
-        msg = f"This value doesn't match pattern {pattern}"
+        msg = f"This value does not match pattern {pattern}"
         raise ValueError(msg)
 
     def text(self, encoding: str = "ascii") -> str:
@@ -354,7 +355,7 @@ def _get_checker(cls, extension_name: str) -> Callable[..., bool]:
         extension_methods = cls._get_extension_methods(extension_name)
         method = extension_methods.get("check")
         if method is None:
-            msg = f"Extension {extension_name} doesn't have a checker method"
+            msg = f"Extension '{extension_name}' does not have a checker method"
             raise NotImplementedError(msg)
         return method
 
@@ -363,7 +364,7 @@ def _get_decoder(cls, extension_name: str) -> Callable[..., BinaPy]:
         extension_methods = cls._get_extension_methods(extension_name)
         method = extension_methods.get("decode")
         if method is None:
-            msg = f"Extension {extension_name} doesn't have a decode method"
+            msg = f"Extension '{extension_name}' does not have a decode method"
             raise NotImplementedError(msg)
         return method
 
@@ -372,7 +373,7 @@ def _get_encoder(cls, extension_name: str) -> Callable[..., BinaPy]:
         extension_methods = cls._get_extension_methods(extension_name)
         method = extension_methods.get("encode")
         if method is None:
-            msg = f"Extension {extension_name} doesn't have an encode method"
+            msg = f"Extension '{extension_name}' does not have an encode method"
             raise NotImplementedError(msg)
         return method
 
@@ -381,7 +382,7 @@ def _get_parser(cls, extension_name: str) -> Callable[..., Any]:
         extension_methods = cls._get_extension_methods(extension_name)
         method = extension_methods.get("parse")
         if method is None:
-            msg = f"Extension {extension_name} doesn't have a parse method"
+            msg = f"Extension '{extension_name}' does not have a parse method"
             raise NotImplementedError(msg)
         return method
 
@@ -390,7 +391,7 @@ def _get_serializer(cls, extension_name: str) -> Callable[..., BinaPy]:
         extension_methods = cls._get_extension_methods(extension_name)
         method = extension_methods.get("serialize")
         if method is None:
-            msg = f"Extension {extension_name} doesn't have a serialize method"
+            msg = f"Extension '{extension_name}' does not have a serialize method"
             raise NotImplementedError(msg)
         return method
 
@@ -440,12 +441,12 @@ def decode_from(self, name: str, *args: Any, **kwargs: Any) -> BinaPy:
 
         return decoder(self, *args, **kwargs)
 
-    def check(self, name: str, *, decode: bool = False, raise_on_error: bool = False) -> bool:  # noqa: PLR0912
+    def check(self, name: str, *, decode: bool = False, raise_on_error: bool = False) -> bool:
         """Check that this BinaPy conforms to a given format extension.
 
         Args:
             name: the name of the extension to check
-            decode: if `True`, and the given extension doesn't have a checker method,
+            decode: if `True`, and the given extension does not have a checker method,
                 try to decode this BinaPy using the decoder method to check if that works.
             raise_on_error: if `True`, exceptions from the checker method, if any,
                 will be raised instead of returning `False`.
@@ -454,7 +455,7 @@ def check(self, name: str, *, decode: bool = False, raise_on_error: bool = False
             a boolean, that is True if this BinaPy conforms to the given extension format, False otherwise.
 
         """
-        # raises an exception in case the extension doesn't exist
+        # raises an exception in case the extension does not exist
         self._get_extension_methods(name)
 
         try:
@@ -468,20 +469,19 @@ def check(self, name: str, *, decode: bool = False, raise_on_error: bool = False
                     raise exc from exc
                 return False
         except NotImplementedError:
-            try:
-                # if checker is not implemented and decode is True, try to decode instead
-                if decode:
-                    decoder = self._get_decoder(name)
-                    try:
-                        decoder(self)
-                    except Exception as exc:
-                        if raise_on_error:
-                            raise exc from exc
-                        return False
-                    else:
-                        return True
-            except NotImplementedError:
-                return False
+            # if checker is not implemented and decode is True, try to decode instead
+            if decode:
+                decoder = self._get_decoder(name)
+                try:
+                    decoder(self)
+                except Exception as exc:
+                    if raise_on_error:
+                        raise exc from exc
+                    return False
+                else:
+                    return True
+            else:
+                raise
         return False
 
     def check_all(self, *, decode: bool = False) -> list[str]:
@@ -498,9 +498,10 @@ def check_all(self, *, decode: bool = False) -> list[str]:
 
         def get_results() -> Iterator[str]:
             for name in self.extensions:
-                success = self.check(name, decode=decode)
-                if success is True:
-                    yield name
+                with suppress(NotImplementedError):
+                    success = self.check(name, decode=decode)
+                    if success is True:
+                        yield name
 
         return list(get_results())
 
diff --git a/tests/test_binapy.py b/tests/test_binapy.py
index a46bcbf..09e2c1b 100644
--- a/tests/test_binapy.py
+++ b/tests/test_binapy.py
@@ -120,6 +120,30 @@ def test_unknown_features() -> None:
     with pytest.raises(NotImplementedError):
         BinaPy.serialize_to("something_not_known", {"foo": "bar"})
 
+    @binapy_encoder("something_known")
+    def encode_something(bp: bytes) -> bytes:
+        return bp
+
+    with pytest.raises(NotImplementedError, match="Extension 'something_known' does not have a decode method"):
+        bp.decode_from("something_known")
+
+    with pytest.raises(NotImplementedError, match="Extension 'something_known' does not have a parse method"):
+        bp.parse_from("something_known")
+
+    with pytest.raises(NotImplementedError, match="Extension 'something_known' does not have a serialize method"):
+        bp.serialize_to("something_known")
+
+    with pytest.raises(NotImplementedError, match="Extension 'something_known' does not have a checker method"):
+        bp.check("something_known")
+
+    @binapy_decoder("something_else")
+    def decode_something_else(bp: bytes) -> bytes:
+        return bp
+
+    with pytest.raises(NotImplementedError, match="Extension 'something_else' does not have an encode method"):
+        bp.encode_to("something_else")
+
+
 
 def test_exceptions() -> None:
     @binapy_decoder("some_feature")
@@ -128,7 +152,8 @@ def decode_some_feature(bp: BinaPy) -> BinaPy:
 
     bp = BinaPy()
 
-    assert bp.check("some_feature") is False
+    with pytest.raises(NotImplementedError):
+        bp.check("some_feature")
     assert bp.check("some_feature", decode=True) is True
 
     @binapy_decoder("other_feature")
@@ -136,7 +161,8 @@ def check_other_feature(bp: BinaPy) -> bool:
         raise ValueError()
 
     bp = BinaPy()
-    assert bp.check("other_feature") is False
+    with pytest.raises(NotImplementedError):
+        bp.check("other_feature")
     assert bp.check("other_feature", decode=True) is False
 
     with pytest.raises(ValueError):
diff --git a/tests/test_json.py b/tests/test_json.py
index e4c91ff..4f190d5 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -1,5 +1,7 @@
 import uuid
+from collections import UserDict
 from datetime import datetime, timedelta, timezone
+from typing import Iterable
 
 from binapy import BinaPy
 
@@ -14,6 +16,12 @@ def test_json() -> None:
 def test_json_encoder() -> None:
     """Datetimes are serialized to integer epoch timestamps, but integer stay integers when
     parsed."""
+
+    user_dict = UserDict({"my": "dict"})
+    def iterable() -> Iterable[int]:
+        for i in range(5):
+            yield i
+
     bp = BinaPy.serialize_to(
         "json",
         {
@@ -26,15 +34,19 @@ def test_json_encoder() -> None:
                 second=40,
                 tzinfo=timezone(timedelta(seconds=0)),
             ),
-            "foo": uuid.UUID("71509952-ec4f-4854-84e7-fa452994b51d"),
+            "uuid": uuid.UUID("71509952-ec4f-4854-84e7-fa452994b51d"),
+            "user_dict": user_dict,
+            "iterable": iterable()
         },
         sort_keys=True,
     )
-    assert bp == b'{"foo":"71509952-ec4f-4854-84e7-fa452994b51d","iat":1600000000}'
+    assert bp == b'{"iat":1600000000,"iterable":[0,1,2,3,4],"user_dict":{"my":"dict"},"uuid":"71509952-ec4f-4854-84e7-fa452994b51d"}'
 
     assert bp.parse_from("json") == {
         "iat": 1600000000,
-        "foo": "71509952-ec4f-4854-84e7-fa452994b51d",
+        "iterable": [0, 1, 2, 3, 4],
+        "uuid": "71509952-ec4f-4854-84e7-fa452994b51d",
+        "user_dict": {"my": "dict"}
     }