diff --git a/src/syndicate/dataspaces.nim b/src/syndicate/dataspaces.nim
index 3f8faab..d9f03a7 100644
--- a/src/syndicate/dataspaces.nim
+++ b/src/syndicate/dataspaces.nim
@@ -172,7 +172,7 @@ proc retract(actor; a: Value) = actor.pendingPatch.adjust(a, -1)
 
 proc install(ep: Endpoint; spec: EndpointSpec) =
   ep.spec = spec
-  if not ep.spec.assertion.isNil:
+  if not ep.spec.assertion.isFalse:
     ep.facet.actor.assert(ep.spec.assertion)
   ep.spec.analysis.map do (a: Analysis):
     assert(not ep.spec.callback.isNil)
@@ -196,7 +196,7 @@ proc abandonQueuedWork(actor) =
 
 proc uninstall(ep: Endpoint; emitPatches: bool) =
   if emitPatches:
-    if not ep.spec.assertion.isNil:
+    if not ep.spec.assertion.isFalse:
       ep.facet.actor.retract(ep.spec.assertion)
   ep.spec.analysis.map do (a: Analysis):
     assert(not ep.spec.callback.isNil)