diff --git a/lib/vm.sx b/lib/vm.sx
index 5af86bc8..af314ad2 100644
--- a/lib/vm.sx
+++ b/lib/vm.sx
@@ -516,6 +516,10 @@
         (vm-push vm (inc (vm-pop vm)))
         (= op 175)
         (vm-push vm (dec (vm-pop vm)))
+        (= op 112)
+        (let
+          ((request (vm-pop vm)))
+          (error (str "VM: IO suspension (OP_PERFORM) — request: " request)))
         :else (error (str "VM: unknown opcode " op))))))
 
 (define