diff --git a/collects/typed-scheme/infer/constraints.rkt b/collects/typed-scheme/infer/constraints.rkt
index e87137c0..2626eb2f 100644
--- a/collects/typed-scheme/infer/constraints.rkt
+++ b/collects/typed-scheme/infer/constraints.rkt
@@ -75,7 +75,7 @@
                           [(map2 dmap2) (in-pairs maps2)])
                          (with-handlers ([exn:infer? (lambda (_) #f)])
                            (cons 
-                            (simple-hash-union map1 map2 (lambda (k v1 v2) (c-meet v1 v2)))
+                            (hash-union map1 map2 #:combine c-meet)
                             (dmap-meet dmap1 dmap2)))))])
       (when (null? maps)
         (fail! maps1 maps2))
diff --git a/collects/typed-scheme/infer/dmap.rkt b/collects/typed-scheme/infer/dmap.rkt
index 1735c49c..7e2e3b39 100644
--- a/collects/typed-scheme/infer/dmap.rkt
+++ b/collects/typed-scheme/infer/dmap.rkt
@@ -62,5 +62,4 @@
 
 (define (dmap-meet dm1 dm2)
   (make-dmap
-   (simple-hash-union (dmap-map dm1) (dmap-map dm2)
-                      (lambda (k dc1 dc2) (dcon-meet dc1 dc2)))))
+   (hash-union (dmap-map dm1) (dmap-map dm2) #:combine dcon-meet)))