diff --git a/fileformats/core/mixin.py b/fileformats/core/mixin.py
index 4e4802f..5bfdbc2 100644
--- a/fileformats/core/mixin.py
+++ b/fileformats/core/mixin.py
@@ -183,12 +183,8 @@ def nested_types(cls) -> ty.Tuple[ty.Type[Classifier], ...]:
     def header(self) -> "fileformats.core.FileSet":
         return self.header_type(self.select_by_ext(self.header_type))  # type: ignore[attr-defined]
 
-    def read_metadata(
-        self, selected_keys: ty.Optional[ty.Collection[str]] = None
-    ) -> ty.Mapping[str, ty.Any]:
+    def read_metadata(self, **kwargs: ty.Any) -> ty.Mapping[str, ty.Any]:
         header: ty.Dict[str, ty.Any] = self.header.load()
-        if selected_keys:
-            header = {k: v for k, v in header.items() if k in selected_keys}
         return header
 
 
@@ -221,10 +217,8 @@ class MyFileFormatWithSideCars(WithSideCars, MyFileFormat):
     def side_cars(self) -> ty.Tuple["fileformats.core.FileSet", ...]:
         return tuple(tp(self.select_by_ext(tp)) for tp in self.side_car_types)  # type: ignore[attr-defined]
 
-    def read_metadata(
-        self, selected_keys: ty.Optional[ty.Collection[str]] = None
-    ) -> ty.Mapping[str, ty.Any]:
-        metadata: ty.Dict[str, ty.Any] = dict(self.primary_type.read_metadata(self, selected_keys=selected_keys))  # type: ignore[arg-type]
+    def read_metadata(self, **kwargs: ty.Any) -> ty.Mapping[str, ty.Any]:
+        metadata: ty.Dict[str, ty.Any] = dict(self.primary_type.read_metadata(self, **kwargs))  # type: ignore[arg-type]
         for side_car in self.side_cars:
             try:
                 side_car_metadata: ty.Dict[str, ty.Any] = side_car.load()
diff --git a/fileformats/core/tests/test_general.py b/fileformats/core/tests/test_general.py
index f9ebf3b..d38f4b2 100644
--- a/fileformats/core/tests/test_general.py
+++ b/fileformats/core/tests/test_general.py
@@ -132,9 +132,7 @@ class ImageWithInlineHeader(File):
 
     header_separator = b"---END HEADER---"
 
-    def read_metadata(
-        self, selected_keys: ty.Optional[ty.Collection[str]] = None
-    ) -> ty.Mapping[str, ty.Any]:
+    def read_metadata(self, **kwargs: ty.Any) -> ty.Mapping[str, ty.Any]:
         hdr = self.contents.split(self.header_separator)[0].decode("utf-8")
         return {k: int(v) for k, v in (ln.split(":") for ln in hdr.splitlines())}
 
diff --git a/fileformats/core/tests/test_mixin.py b/fileformats/core/tests/test_mixin.py
index b15f904..dde47fe 100644
--- a/fileformats/core/tests/test_mixin.py
+++ b/fileformats/core/tests/test_mixin.py
@@ -107,9 +107,7 @@ class ImageWithInlineHeader(File):
 
     header_separator = b"---END HEADER---"
 
-    def read_metadata(
-        self, selected_keys: ty.Optional[ty.Collection[str]] = None
-    ) -> ty.Mapping[str, ty.Any]:
+    def read_metadata(self, **kwargs: ty.Any) -> ty.Mapping[str, ty.Any]:
         hdr = self.contents.split(self.header_separator)[0].decode("utf-8")
         return dict(ln.split(":") for ln in hdr.splitlines())