diff --git a/internal/cmd/docgen/main.go b/internal/cmd/docgen/main.go
index 9d79574..33e78e3 100644
--- a/internal/cmd/docgen/main.go
+++ b/internal/cmd/docgen/main.go
@@ -42,6 +42,8 @@ func mainerr() (err error) {
 	// Initialize template.
 	t := template.New("doc")
 
+	t.Option("missingkey=error")
+
 	t.Funcs(template.FuncMap{
 		"include": include,
 		"snippet": snippet,