diff --git a/packages/context-state/src/finalizationRegistry.ts b/packages/context-state/src/finalizationRegistry.ts
deleted file mode 100644
index ad99261..0000000
--- a/packages/context-state/src/finalizationRegistry.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-import "expose-gc"
-
-export function testFinalizationRegistry() {
-  const promises = new Map<
-    string,
-    Promise<string> & { resolve: (tag: string) => void }
-  >()
-
-  const finalizationRegistry = new FinalizationRegistry((tag: any) => {
-    if (!promises.has(tag)) {
-      const promise = Object.assign(Promise.resolve(tag), { resolve: () => {} })
-      promises.set(tag, promise)
-    } else {
-      promises.get(tag)!.resolve(tag)
-    }
-  })
-  function tag<T extends object>(tag: string, v: T) {
-    if (!promises.has(tag)) {
-      let resolve = (_tag: string) => {}
-      const promise = new Promise<string>((res) => {
-        resolve = res
-      })
-      Object.assign(promise, { resolve })
-      promises.set(tag, promise as any)
-      finalizationRegistry.register(v, tag)
-    }
-    return v
-  }
-
-  return {
-    tag,
-    getPromise(tag: string) {
-      return promises.get(tag)!
-    },
-    gc() {
-      global.gc!()
-    },
-  }
-}
diff --git a/packages/context-state/src/substate.test.ts b/packages/context-state/src/substate.test.ts
index 9295aba..e004e3d 100644
--- a/packages/context-state/src/substate.test.ts
+++ b/packages/context-state/src/substate.test.ts
@@ -14,7 +14,7 @@ import {
 } from "rxjs"
 import { createRoot } from "./create-root"
 import { createSignal } from "./create-signal"
-import { testFinalizationRegistry } from "./finalizationRegistry"
+import { testFinalizationRegistry } from "./test-utils/finalizationRegistry"
 import { routeState } from "./route-state"
 import { substate } from "./substate"
 
@@ -515,15 +515,12 @@ describe("subState", () => {
       const nodeA = substate(root, () =>
         fr.tag("nodeA", concat(from([1, 2, 3]), NEVER)),
       )
-      fr.gc()
-
       const stop = root.run()
 
       expect(nodeA.getValue()).toEqual(3)
       stop()
-      fr.gc()
 
-      await expect(fr.getPromise("nodeA")).resolves.toEqual("nodeA")
+      await fr.assertFinalized("nodeA")
     })
 
     it("doesn't hold references to dead instances, even on circular references", async () => {
@@ -550,7 +547,6 @@ describe("subState", () => {
             getState$(nodeA).pipe(map((v) => v + "$b$")),
           ),
       )
-      fr.gc()
 
       root.run("b")
       const stopA = root.run("a")
@@ -560,10 +556,9 @@ describe("subState", () => {
       signal.push({ gameId: "a" }, null)
       expect(nodeA.getValue({ gameId: "a" })).toEqual("/a/$b$/a/$b$/a/")
       stopA()
-      fr.gc()
 
-      await expect(fr.getPromise("nodeA-a")).resolves.toBe("nodeA-a")
-      await expect(fr.getPromise("nodeB-a")).resolves.toBe("nodeB-a")
+      await fr.assertFinalized("nodeA-a")
+      await fr.assertFinalized("nodeB-a")
     })
   })
 })
diff --git a/packages/context-state/src/test-utils/finalizationRegistry.ts b/packages/context-state/src/test-utils/finalizationRegistry.ts
new file mode 100644
index 0000000..c10cdf9
--- /dev/null
+++ b/packages/context-state/src/test-utils/finalizationRegistry.ts
@@ -0,0 +1,38 @@
+import "expose-gc"
+
+export function testFinalizationRegistry() {
+  const promises = new Map<
+    string,
+    Promise<string> & { resolve: (tag: string) => void }
+  >()
+
+  const finalizationRegistry = new FinalizationRegistry((tag: any) => {
+    promises.get(tag)!.resolve(tag)
+  })
+  function tag<T extends object>(tag: string, v: T) {
+    if (promises.has(tag)) {
+      throw new Error("TestFinalizationRegistry: tags must be unique")
+    }
+    let resolve = (_tag: string) => {}
+    const promise = new Promise<string>((res) => {
+      resolve = res
+    })
+    Object.assign(promise, { resolve })
+    promises.set(tag, promise as any)
+    finalizationRegistry.register(v, tag)
+    return v
+  }
+
+  return {
+    tag,
+    assertFinalized(tag: string) {
+      global.gc!()
+      const promise = promises.get(tag)
+      expect(promise).not.toBe(undefined)
+      // I was doing expect(promise).resolves.toEqual(tag), but that's not testing what it should
+      // `promise` will resolve when the object gets garbage-collected, if it doesn't, the test times out.
+      // This is equivalent to just awaiting the promise:
+      return promise
+    },
+  }
+}