diff --git a/src/main.el b/src/main.el
index 254b1fd..ef491a3 100644
--- a/src/main.el
+++ b/src/main.el
@@ -698,12 +698,12 @@ fn handle_request_inner(method: String, path: String, headers: Map, body: String
         }
 
         // Free tier: $0 PaymentIntent for age verification (18+ requirement).
-        // Card is verified and saved (setup_future_usage=off_session). No charge.
+        // Verifies card is valid. No charge, no capture.
+        // Note: setup_future_usage cannot be used with amount=0.
         if str_eq(plan, "free") {
             let free_pi_body: String = "amount=0"
                 + "&currency=usd"
                 + "&payment_method_types[]=card"
-                + "&setup_future_usage=off_session"
                 + "&metadata[plan]=free"
                 + "&metadata[purpose]=age_verification"
             let free_pi_body = if !str_eq(pi_cus_id, "") { free_pi_body + "&customer=" + pi_cus_id } else { free_pi_body }