diff --git a/src/signal.ts b/src/signal.ts
index 780243ff..95c1af2a 100644
--- a/src/signal.ts
+++ b/src/signal.ts
@@ -7,6 +7,12 @@ function baseEquality<T>(oldValue: T, newValue: T) {
 }
 
 export class Signal<T = unknown> {
+/**
+  @private This is available for internal "friend" APIs to use, but it is *not*
+    legal to use by consumers.
+ */
+export const Peek = Symbol('Peek');
+
   #value: T;
   protected isEqual: Equality<T>;
   protected tag: Tag;
@@ -27,7 +33,12 @@ export class Signal<T = unknown> {
     return this.#value;
   }
 
-  peek() {
+  // Expressly *not* part of the public API: peeking a value in contexts other than internal parts
+  // of the reactivity system itself tends very strongly to produce bugs, because it decouples
+  // consumers from the root state. (It is very, very tempting to wire your own caching on with a
+  // "peek", rather than using caching tools composed out of the core primitives, or to "be smarter"
+  // than the signal system.)
+  [Peek](): T {
     return this.#value;
   }
 
diff --git a/tests/signal.spec.ts b/tests/signal.spec.ts
index c131c5e1..04d6dd1c 100644
--- a/tests/signal.spec.ts
+++ b/tests/signal.spec.ts
@@ -1,5 +1,5 @@
 import { expect, describe, test, vi } from 'vitest';
-import { createSignal } from '../src/signal';
+import { createSignal, Peek } from '../src/signal';
 import { createEffect } from '../src/effect';
 import isEqual from 'lodash/isEqual';
 
@@ -50,7 +50,7 @@ describe('Signal', () => {
     let foo = createSignal('foo');
 
     let spy = vi.fn(() => {
-      foo.peek();
+      foo[Peek]();
     });
 
     createEffect(spy);