diff --git a/tools/render b/tools/render
index 4150951..96a90c0 100755
--- a/tools/render
+++ b/tools/render
@@ -19,11 +19,18 @@ ROOT = pathlib.Path(REPO.working_dir)
 NODES = ROOT.joinpath("nodes")
 SCHEMATICS = ROOT.joinpath("schematics")
 RENDERED = ROOT.joinpath("rendered")
+
+EXTENSIONS = ["jinja2.ext.do"]
+
 PATCHES = Environment(
-    loader=FileSystemLoader(ROOT.joinpath("patches")), undefined=StrictUndefined
+    loader=FileSystemLoader(ROOT.joinpath("patches")),
+    undefined=StrictUndefined,
+    extensions=EXTENSIONS,
 )
 TEMPLATES = Environment(
-    loader=FileSystemLoader(ROOT.joinpath("templates")), undefined=StrictUndefined
+    loader=FileSystemLoader(ROOT.joinpath("templates")),
+    undefined=StrictUndefined,
+    extensions=EXTENSIONS,
 )