diff --git a/syndicate/dataspace.rkt b/syndicate/dataspace.rkt
index 584ed60..4477dac 100644
--- a/syndicate/dataspace.rkt
+++ b/syndicate/dataspace.rkt
@@ -232,7 +232,7 @@
                            (make-queue)
                            (set->bag filtered-initial-assertions)))
   (for [(a filtered-initial-assertions)]
-    (match (bag-change! (dataspace-assertions ds) a 1)
+    (match (bag-change! (dataspace-assertions ds) a +1)
       ['absent->present (add-assertion! (dataspace-routing-table ds) a)]
       ;; 'absent->absent and 'present->absent absurd
       ['present->present (void)])) ;; i.e. no visible change