diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4cd9a8e88..d7ef2d0da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,9 @@
-# 0.41.0
+# 0.42.1
+
+- Add assertSingletonPackage to util
+- Ensure that only a single keyring instance is loaded (uses above)
+
+# 0.41.1
 
 - Extensions to the client-specific database interfaces (non-breaking for API and util users)
 
diff --git a/packages/keyring/src/index.ts b/packages/keyring/src/index.ts
index 567b84cb5..9ab68cabb 100644
--- a/packages/keyring/src/index.ts
+++ b/packages/keyring/src/index.ts
@@ -5,7 +5,7 @@
 import { KeypairType } from '@polkadot/util-crypto/types';
 import { KeyringInstance, KeyringPair, KeyringPair$Json, KeyringPair$Meta, KeyringOptions } from './types';
 
-import { assert, hexToU8a, isNumber, isHex, stringToU8a } from '@polkadot/util';
+import { assert, assertSingletonPackage, hexToU8a, isNumber, isHex, stringToU8a } from '@polkadot/util';
 import { keyExtractSuri, mnemonicToSeed , naclKeypairFromSeed as naclFromSeed, schnorrkelKeypairFromSeed as schnorrkelFromSeed, mnemonicToMiniSecret, keyFromPath } from '@polkadot/util-crypto';
 
 import { decodeAddress, encodeAddress, setAddressPrefix } from './address';
@@ -13,6 +13,8 @@ import { DEV_PHRASE } from './defaults';
 import createPair from './pair';
 import Pairs from './pairs';
 
+assertSingletonPackage('@polkadot/keyring');
+
 /**
  * # @polkadot/keyring
  *
diff --git a/packages/util/src/assertSingletonPackage.spec.ts b/packages/util/src/assertSingletonPackage.spec.ts
new file mode 100644
index 000000000..9fc763c69
--- /dev/null
+++ b/packages/util/src/assertSingletonPackage.spec.ts
@@ -0,0 +1,21 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { assertSingletonPackage } from '.';
+
+describe('assertSingletonPackage', () => {
+  const NAME = 'assertSingletonPackage';
+
+  it('should not throw the first time', () => {
+    expect(
+      () => assertSingletonPackage(NAME)
+    ).not.toThrow();
+  });
+
+  it('should throw the second time', () => {
+    expect(
+      () => assertSingletonPackage(NAME)
+    ).toThrow(/Multiple versions of assertSingletonPackage detected/);
+  });
+});
diff --git a/packages/util/src/assertSingletonPackage.ts b/packages/util/src/assertSingletonPackage.ts
new file mode 100644
index 000000000..77ed9de19
--- /dev/null
+++ b/packages/util/src/assertSingletonPackage.ts
@@ -0,0 +1,22 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import isUndefined from './is/undefined';
+import assert from './assert';
+
+/**
+ * @name assertSingletonPackage
+ * @summary Checks that a specific package is only imported once
+ */
+export default function assertSingletonPackage (name: string): void {
+  const _global: any = isUndefined(window) ? global : window;
+
+  if (isUndefined(_global.__polkadotjs)) {
+    _global.__polkadotjs = {};
+  }
+
+  assert(isUndefined(_global.__polkadotjs[name]), `Multiple versions of ${name} detected, ensure that there is only version one in your dependency tree`);
+
+  _global.__polkadotjs[name] = true;
+}
diff --git a/packages/util/src/index.ts b/packages/util/src/index.ts
index d756c198f..b4c3a5f9b 100644
--- a/packages/util/src/index.ts
+++ b/packages/util/src/index.ts
@@ -9,6 +9,7 @@ import './polyfill';
  */
 
 export { default as assert } from './assert';
+export { default as assertSingletonPackage } from './assertSingletonPackage';
 export { default as logger } from './logger';
 export { default as promisify } from './promisify';