diff --git a/knots/timeout.scm b/knots/timeout.scm
index 552d079..21c2267 100644
--- a/knots/timeout.scm
+++ b/knots/timeout.scm
@@ -119,17 +119,19 @@
 
 (define (make-wait-operation ready? schedule-when-ready port
                              port-ready-fd this-procedure)
-  (make-base-operation #f
-                       (lambda _
-                         (and (ready? port) values))
-                       (lambda (flag sched resume)
-                         (define (commit)
-                           (match (atomic-box-compare-and-swap! flag 'W 'S)
-                             ('W (resume values))
-                             ('C (commit))
-                             ('S #f)))
-                         (schedule-when-ready
-                          sched (port-ready-fd port) commit))))
+  ((module-ref (resolve-interface '(fibers operations))
+               'make-base-operation)
+   #f
+   (lambda _
+     (and (ready? port) values))
+   (lambda (flag sched resume)
+     (define (commit)
+       (match (atomic-box-compare-and-swap! flag 'W 'S)
+         ('W (resume values))
+         ('C (commit))
+         ('S #f)))
+     (schedule-when-ready
+      sched (port-ready-fd port) commit))))
 
 (define (wait-until-port-readable-operation port)
   "Make an operation that will succeed when PORT is readable."