diff --git a/quartodoc/autosummary.py b/quartodoc/autosummary.py
index c6bea4e..94b0dfc 100644
--- a/quartodoc/autosummary.py
+++ b/quartodoc/autosummary.py
@@ -444,7 +444,8 @@ class Builder:
     parser:
         Docstring parser to use. This correspond to different docstring styles,
         and can be one of "google", "sphinx", and "numpy". Defaults to "numpy".
-
+    kwargs:
+        Additional options are ignored with a warning for forwards compatibility.
     """
 
     # builder dispatching ----
@@ -495,6 +496,7 @@ def __init__(
         parser="numpy",
         render_interlinks: bool = False,
         _fast_inventory=False,
+        **kwargs: Any
     ):
         self.layout = self.load_layout(
             sections=sections, package=package, options=options
@@ -508,6 +510,15 @@ def __init__(
         self.css = css
         self.parser = parser
 
+        if len(kwargs) > 0:
+            ignored_keys = [f"'{k}'" for k in kwargs.keys()]
+            text_options = "option" if len(kwargs) == 1 else "options"
+            raise ValueError(
+                f"Unknown quartodoc {text_options}: {', '.join(ignored_keys)}. "
+                "Please see <https://machow.github.io/quartodoc/get-started/basic-docs.html> "
+                "for quartodoc site configuration options."
+            )
+
         self.renderer = Renderer.from_config(renderer)
         if render_interlinks:
             # this is a top-level option, but lives on the renderer
diff --git a/quartodoc/tests/test_builder.py b/quartodoc/tests/test_builder.py
index 932bc97..27f8dc6 100644
--- a/quartodoc/tests/test_builder.py
+++ b/quartodoc/tests/test_builder.py
@@ -58,6 +58,22 @@ def test_builder_auto_options():
     builder = Builder.from_quarto_config(cfg)
     assert builder.layout.options.members == ["a_func", "a_attr"]
 
+def test_builder_error_unknown_options():
+    cfg = yaml.safe_load(
+        """
+    quartodoc:
+      package: quartodoc
+      this_is_not_a_real_option: true
+      options:
+        members: [a_func, a_attr]
+      sections:
+        - contents: [quartodoc.tests.example]
+    """
+    )
+
+    with pytest.raises(ValueError):
+      Builder.from_quarto_config(cfg)
+
 
 def test_builder_generate_sidebar(tmp_path, snapshot):
     cfg = yaml.safe_load(