diff --git a/vm.c b/vm.c
index 3719ab8e9a..b7184f4e1c 100644
--- a/vm.c
+++ b/vm.c
@@ -2380,7 +2380,7 @@ rb_execution_context_mark(const rb_execution_context_t *ec)
 	while (cfp != limit_cfp) {
 #if VM_CHECK_MODE > 0
 	    const VALUE *ep = cfp->ep;
-	    VM_ASSERT(!!VM_ENV_FLAGS(ep, VM_ENV_FLAG_ESCAPED) == vm_ep_in_heap_p_(th, ep));
+	    VM_ASSERT(!!VM_ENV_FLAGS(ep, VM_ENV_FLAG_ESCAPED) == vm_ep_in_heap_p_(GET_THREAD(), ep));
 #endif
 	    rb_gc_mark(cfp->self);
 	    rb_gc_mark((VALUE)cfp->iseq);