diff --git a/docs/examples/porch/middleware/idempotent.wo b/docs/examples/porch/middleware/idempotent.wo
index 046f784..a8e55ee 100644
--- a/docs/examples/porch/middleware/idempotent.wo
+++ b/docs/examples/porch/middleware/idempotent.wo
@@ -5,6 +5,7 @@
 
 use time
 use http
+use json
 
 -- Idempotent middleware: before (check/replay) + after (store on miss).
 -- Key composition: "idem:${header}" or "idem:${header}:${sha256(method|path|body)}"