diff --git a/main.ts b/main.ts
index 84f0314..c77ca8b 100644
--- a/main.ts
+++ b/main.ts
@@ -17,19 +17,11 @@ const Observe = Record.makeConstructor<Ref<Entity>>('Observe', ['label', 'observ
 function makeDataspace(): Entity {
     const handleMap: IdentityMap<Handle, Assertion> = new IdentityMap();
     const assertions = new Bag<Ref<Entity>>();
-    const subscriptions: Dictionary<Dictionary<Dictionary<Handle>>> = new Dictionary();
+    const subscriptions: Dictionary<Map<Ref<Entity>, Dictionary<Handle>>> = new Dictionary();
 
     function forEachSubscription(assertion: Assertion, f: (handleMap: Dictionary<Handle>, peer: Ref<Entity>) => void): void {
-        if (Record.isRecord(assertion)) {
-            const peerMap = subscriptions.get(assertion.label);
-            if (Dictionary.isDictionary(peerMap)) {
-                peerMap.forEach((handleMap, peer) => {
-                    if (peer instanceof Ref) {
-                        f(handleMap, peer);
-                    }
-                });
-            }
-        }
+        if (!Record.isRecord(assertion)) return;
+        subscriptions.get(assertion.label)?.forEach(f);
     }
 
     return {
@@ -42,7 +34,7 @@ function makeDataspace(): Entity {
                     const observer = Observe._.observer(assertion) as Ref<Entity>;
                     let peerMap = subscriptions.get(observedLabel);
                     if (peerMap === void 0) {
-                        peerMap = new Dictionary();
+                        peerMap = new Map();
                         subscriptions.set(observedLabel, peerMap);
                     }
                     const handleMap: Dictionary<Handle> = new Dictionary();
@@ -78,7 +70,7 @@ function makeDataspace(): Entity {
                     });
                     if (Observe.isClassOf(assertion)) {
                         let peerMap = subscriptions.get(Observe._.label(assertion)!)!;
-                        peerMap.delete(Observe._.observer(assertion)!);
+                        peerMap.delete(Observe._.observer(assertion)! as Ref<Entity>);
                         if (peerMap.size === 0) subscriptions.delete(Observe._.label(assertion)!);
                     }
                 }