diff --git a/networks.rkt b/networks.rkt
index b7a8b91..ccd2a8a 100644
--- a/networks.rkt
+++ b/networks.rkt
@@ -511,8 +511,8 @@
 (define (build-interaction-graph network doms)
   (define vars (hash-keys network))
   (unweighted-graph/directed
-   (for*/list ([x vars]
-               [y vars]
+   (for*/list ([x (in-list vars)]
+               [y (in-list vars)]
                #:when (interaction? network doms x y))
      (list x y))))