diff --git a/gnu/build/dbus-service.scm b/gnu/build/dbus-service.scm
index c5671396e2..3ae45ad755 100644
--- a/gnu/build/dbus-service.scm
+++ b/gnu/build/dbus-service.scm
@@ -64,10 +64,10 @@
 ;;; which is required at least for the Jami service.
 (define sleep*
   (lambda ()                            ;delay execution
-    (if (resolve-module '(fibers) #f)
+    (if (resolve-module '(fibers) #f #:ensure #f)
         (module-ref (resolve-interface '(fibers)) 'sleep)
         (begin
-          (format #f "fibers not available -- blocking 'sleep' in use")
+          (format #t "Fibers not available -- blocking 'sleep' in use~%")
           sleep))))
 
 ;;;
diff --git a/gnu/build/secret-service.scm b/gnu/build/secret-service.scm
index b362b901be..c53145c8e7 100644
--- a/gnu/build/secret-service.scm
+++ b/gnu/build/secret-service.scm
@@ -62,7 +62,7 @@ bindings available within the lexical scope of BODY."
 (define (wait-for-readable-fd port timeout)
   "Wait until PORT has data available for reading or TIMEOUT has expired.
 Return #t in the former case and #f in the latter case."
-  (match (resolve-module '(fibers) #f)            ;using Fibers?
+  (match (resolve-module '(fibers) #f #:ensure #f) ;using Fibers?
     (#f
      (log "blocking on socket...~%")
      (match (select (list port) '() '() timeout)