diff --git a/packages/eslint-scope/lib/assert.js b/packages/eslint-scope/lib/assert.js
new file mode 100644
index 00000000..6300bce7
--- /dev/null
+++ b/packages/eslint-scope/lib/assert.js
@@ -0,0 +1,17 @@
+/**
+ * @fileoverview Assertion utilities.
+ * @author Nicholas C. Zakas
+ */
+
+/**
+ * Throws an error if the given condition is not truthy.
+ * @param {boolean} condition The condition to check.
+ * @param {string} message The message to include with the error.
+ * @returns {void}
+ * @throws {Error} When the condition is not truthy.
+ */
+export function assert(condition, message = "Assertion failed.") {
+    if (!condition) {
+        throw new Error(message);
+    }
+}
diff --git a/packages/eslint-scope/lib/index.js b/packages/eslint-scope/lib/index.js
index 5a27d062..7e79c923 100644
--- a/packages/eslint-scope/lib/index.js
+++ b/packages/eslint-scope/lib/index.js
@@ -46,7 +46,7 @@
  * @module escope
  */
 
-import assert from "node:assert";
+import { assert } from "./assert.js";
 
 import ScopeManager from "./scope-manager.js";
 import Referencer from "./referencer.js";
diff --git a/packages/eslint-scope/lib/referencer.js b/packages/eslint-scope/lib/referencer.js
index cf6ea999..f939aa83 100644
--- a/packages/eslint-scope/lib/referencer.js
+++ b/packages/eslint-scope/lib/referencer.js
@@ -28,7 +28,7 @@ import Reference from "./reference.js";
 import Variable from "./variable.js";
 import PatternVisitor from "./pattern-visitor.js";
 import { Definition, ParameterDefinition } from "./definition.js";
-import assert from "node:assert";
+import { assert } from "./assert.js";
 
 const { Syntax } = estraverse;
 
diff --git a/packages/eslint-scope/lib/scope-manager.js b/packages/eslint-scope/lib/scope-manager.js
index 077b0491..a136648f 100644
--- a/packages/eslint-scope/lib/scope-manager.js
+++ b/packages/eslint-scope/lib/scope-manager.js
@@ -36,7 +36,7 @@ import {
     SwitchScope,
     WithScope
 } from "./scope.js";
-import assert from "node:assert";
+import { assert } from "./assert.js";
 
 /**
  * @constructor ScopeManager
diff --git a/packages/eslint-scope/lib/scope.js b/packages/eslint-scope/lib/scope.js
index 6c3f3cfe..b3ef0266 100644
--- a/packages/eslint-scope/lib/scope.js
+++ b/packages/eslint-scope/lib/scope.js
@@ -27,7 +27,7 @@ import estraverse from "estraverse";
 import Reference from "./reference.js";
 import Variable from "./variable.js";
 import { Definition } from "./definition.js";
-import assert from "node:assert";
+import { assert } from "./assert.js";
 
 const { Syntax } = estraverse;