diff --git a/runtime/wasm/effect-native.wat b/runtime/wasm/effect-native.wat
index a8e8694cfd..9a283dba84 100644
--- a/runtime/wasm/effect-native.wat
+++ b/runtime/wasm/effect-native.wat
@@ -17,6 +17,7 @@
       (func $caml_wrap_exception (param externref) (result (ref eq))))
    (import "stdlib" "caml_main_wrapper"
       (global $caml_main_wrapper (mut (ref null $wrapper_func))))
+   (import "effect" "effect_allowed" (global $effect_allowed (mut i32)))
 
    (type $block (array (mut (ref eq))))
    (type $string (array (mut i8)))
@@ -180,6 +181,10 @@
 
    (func (export "%perform") (param $eff (ref eq)) (result (ref eq))
       (local $res (tuple (ref eq) (ref eq)))
+      (if (i32.eqz (global.get $effect_allowed))
+         (then
+            (return_call $raise_unhandled
+               (local.get $eff) (ref.i31 (i32.const 0)))))
       (local.set $res (suspend $effect (local.get $eff)))
       (return_call_ref $function_1 (tuple.extract 2 1 (local.get $res))
          (tuple.extract 2 0 (local.get $res))
diff --git a/runtime/wasm/effect.wat b/runtime/wasm/effect.wat
index bc579dd9ec..cdc49ba58a 100644
--- a/runtime/wasm/effect.wat
+++ b/runtime/wasm/effect.wat
@@ -80,7 +80,7 @@
             (call $caml_fresh_oo_id (ref.i31 (i32.const 0)))))
       (ref.i31 (i32.const 0)))
 
-   (global $effect_allowed (mut i32) (i32.const 1))
+   (global $effect_allowed (export "effect_allowed") (mut i32) (i32.const 1))
 
 (@if (not wasi)
 (@then