diff --git a/omicron/ssg/__init__.py b/omicron/ssg/__init__.py
index e69de29..276d592 100644
--- a/omicron/ssg/__init__.py
+++ b/omicron/ssg/__init__.py
@@ -0,0 +1,11 @@
+import os
+
+typechecked = os.environ.get("OSSG_TYPECHECKED")
+if typechecked == "all":
+    from beartype.claw import beartype_all
+
+    beartype_all()
+elif typechecked:
+    from beartype.claw import beartype_this_package
+
+    beartype_this_package()
diff --git a/omicron/ssg/content.py b/omicron/ssg/content.py
index cd85eff..8efce91 100644
--- a/omicron/ssg/content.py
+++ b/omicron/ssg/content.py
@@ -7,6 +7,8 @@ from typing import TYPE_CHECKING, Any, cast
 
 if TYPE_CHECKING:
     from omicron.ssg.site import Site
+else:
+    Site = "omicron.ssg.site.Site"
 
 import yaml
 from markupsafe import Markup
diff --git a/pyproject.toml b/pyproject.toml
index 53f4759..bac77f6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,7 @@ dependencies = [
 
 [project.optional-dependencies]
 dev = [
+    "beartype",
     "black",
     "mypy",
     "types-PyYAML",