diff --git a/packages/core/src/dataspace.js b/packages/core/src/dataspace.js
index 660f34a..8eb633e 100644
--- a/packages/core/src/dataspace.js
+++ b/packages/core/src/dataspace.js
@@ -18,7 +18,7 @@
 //---------------------------------------------------------------------------
 
 const Immutable = require("immutable");
-const { fromJS } = require("preserves");
+const Preserves = require("preserves");
 
 const Skeleton = require('./skeleton.js');
 const $Special = require('./special.js');
@@ -130,7 +130,10 @@ Dataspace.declareField = function (obj, prop, init) {
       obj,
       prop,
       init,
-      { objectId: Immutable.List.of(obj, prop) });
+      {
+        objectId: Immutable.List.of(obj, prop),
+        noopGuard: Preserves.is
+      });
   }
 };
 
@@ -344,14 +347,14 @@ Actor.prototype.assert = function (a) { this.pendingPatch().adjust(a, +1); };
 Actor.prototype.retract = function (a) { this.pendingPatch().adjust(a, -1); };
 
 Actor.prototype.adhocRetract = function (a) {
-  a = fromJS(a);
+  a = Preserves.fromJS(a);
   if (this.adhocAssertions.change(a, -1, true) === Bag.PRESENT_TO_ABSENT) {
     this.retract(a);
   }
 };
 
 Actor.prototype.adhocAssert = function (a) {
-  a = fromJS(a);
+  a = Preserves.fromJS(a);
   if (this.adhocAssertions.change(a, +1) === Bag.ABSENT_TO_PRESENT) {
     this.assert(a);
   }
@@ -374,7 +377,7 @@ Patch.prototype.perform = function (ds, ac) {
 Patch.prototype.adjust = function (a, count) {
   if (a !== void 0) {
     var _net;
-    ({bag: this.changes, net: _net} = Bag.change(this.changes, fromJS(a), count));
+    ({bag: this.changes, net: _net} = Bag.change(this.changes, Preserves.fromJS(a), count));
   }
 };
 
@@ -384,7 +387,7 @@ function Message(body) {
 
 Message.prototype.perform = function (ds, ac) {
   if (this.body !== void 0) {
-    ds.sendMessage(fromJS(this.body));
+    ds.sendMessage(Preserves.fromJS(this.body));
   }
 };
 
@@ -617,7 +620,7 @@ Endpoint.prototype._uninstall = function (ds, ac, emitPatches) {
 
 Endpoint.prototype.refresh = function (ds, ac, facet) {
   let [newAssertion, newHandler] = this.updateFun.call(facet.fields);
-  if (newAssertion !== void 0) newAssertion = fromJS(newAssertion);
+  if (newAssertion !== void 0) newAssertion = Preserves.fromJS(newAssertion);
   if (!Immutable.is(newAssertion, this.assertion)) {
     this._uninstall(ds, ac, true);
     this._install(ds, ac, newAssertion, newHandler);