diff --git a/.eslintrc.json b/.eslintrc.json
index d009780f372..95c6e99a813 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -276,7 +276,8 @@
             "patterns": [
               "**/../lib/**",
               "mongodb-mock-server",
-              "node:*"
+              "node:*",
+              "os"
             ],
             "paths": [
               {
@@ -327,4 +328,4 @@
       }
     }
   ]
-}
+}
\ No newline at end of file
diff --git a/src/cmap/auth/gssapi.ts b/src/cmap/auth/gssapi.ts
index d18cb6b360e..0154057919f 100644
--- a/src/cmap/auth/gssapi.ts
+++ b/src/cmap/auth/gssapi.ts
@@ -1,5 +1,4 @@
 import * as dns from 'dns';
-import * as os from 'os';
 
 import { getKerberos, type Kerberos, type KerberosClient } from '../../deps';
 import { MongoInvalidArgumentError, MongoMissingCredentialsError } from '../../error';
@@ -69,9 +68,13 @@ export class GSSAPI extends AuthProvider {
   }
 }
 
-async function makeKerberosClient(authContext: AuthContext): Promise<KerberosClient> {
-  const { hostAddress } = authContext.options;
-  const { credentials } = authContext;
+async function makeKerberosClient({
+  options: {
+    hostAddress,
+    runtime: { os }
+  },
+  credentials
+}: AuthContext): Promise<KerberosClient> {
   if (!hostAddress || typeof hostAddress.host !== 'string' || !credentials) {
     throw new MongoInvalidArgumentError(
       'Connection must have host and port and credentials defined.'
diff --git a/src/cmap/connection.ts b/src/cmap/connection.ts
index 9652e3a5e4f..dfffb15daeb 100644
--- a/src/cmap/connection.ts
+++ b/src/cmap/connection.ts
@@ -35,6 +35,7 @@ import { type MongoClientAuthProviders } from '../mongo_client_auth_providers';
 import { MongoLoggableComponent, type MongoLogger, SeverityLevel } from '../mongo_logger';
 import { type Abortable, type CancellationToken, TypedEventEmitter } from '../mongo_types';
 import { ReadPreference, type ReadPreferenceLike } from '../read_preference';
+import { type Runtime } from '../runtime_adapters';
 import { ServerType } from '../sdam/common';
 import { applySession, type ClientSession, updateSessionFromResponse } from '../sessions';
 import { type TimeoutContext, TimeoutError } from '../timeout';
@@ -143,6 +144,8 @@ export interface ConnectionOptions
   metadata: Promise<ClientMetadata>;
   /** @internal */
   mongoLogger?: MongoLogger | undefined;
+  /** @internal */
+  runtime: Runtime;
 }
 
 /** @public */
diff --git a/src/cmap/handshake/client_metadata.ts b/src/cmap/handshake/client_metadata.ts
index 48cb6a47350..3b79e1df48f 100644
--- a/src/cmap/handshake/client_metadata.ts
+++ b/src/cmap/handshake/client_metadata.ts
@@ -1,4 +1,3 @@
-import * as os from 'os';
 import * as process from 'process';
 
 import { BSON, type Document, Int32, NumberUtils } from '../../bson';
@@ -96,7 +95,8 @@ export class LimitedSizeDocument {
   }
 }
 
-type MakeClientMetadataOptions = Pick<MongoOptions, 'appName'>;
+type MakeClientMetadataOptions = Pick<MongoOptions, 'appName' | 'runtime'>;
+
 /**
  * From the specs:
  * Implementors SHOULD cumulatively update fields in the following order until the document is under the size limit:
@@ -107,7 +107,7 @@ type MakeClientMetadataOptions = Pick<MongoOptions, 'appName'>;
  */
 export async function makeClientMetadata(
   driverInfoList: DriverInfo[],
-  { appName = '' }: MakeClientMetadataOptions
+  { appName = '', runtime: { os } }: MakeClientMetadataOptions
 ): Promise<ClientMetadata> {
   const metadataDocument = new LimitedSizeDocument(512);
 
diff --git a/src/connection_string.ts b/src/connection_string.ts
index df6dfc607a0..06315a96869 100644
--- a/src/connection_string.ts
+++ b/src/connection_string.ts
@@ -20,6 +20,7 @@ import {
 import { MongoLoggableComponent, MongoLogger, SeverityLevel } from './mongo_logger';
 import { ReadConcern, type ReadConcernLevel } from './read_concern';
 import { ReadPreference, type ReadPreferenceMode } from './read_preference';
+import { resolveRuntimeAdapters } from './runtime_adapters';
 import { ServerMonitoringMode } from './sdam/monitor';
 import type { TagSet } from './sdam/server_description';
 import {
@@ -538,6 +539,8 @@ export function parseOptions(
     }
   );
 
+  mongoOptions.runtime = resolveRuntimeAdapters(options);
+
   return mongoOptions;
 }
 
@@ -1061,6 +1064,9 @@ export const OPTIONS = {
     default: true,
     type: 'boolean'
   },
+  runtimeAdapters: {
+    type: 'record'
+  },
   serializeFunctions: {
     type: 'boolean'
   },
diff --git a/src/index.ts b/src/index.ts
index 8f5c4cfa60e..74803dfa2a0 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -562,6 +562,7 @@ export type {
   ReadPreferenceLikeOptions,
   ReadPreferenceOptions
 } from './read_preference';
+export type { OsAdapter, Runtime, RuntimeAdapters } from './runtime_adapters';
 export type { ClusterTime } from './sdam/common';
 export type {
   Monitor,
diff --git a/src/mongo_client.ts b/src/mongo_client.ts
index 970f0f88061..87d969fee93 100644
--- a/src/mongo_client.ts
+++ b/src/mongo_client.ts
@@ -46,6 +46,7 @@ import { EndSessionsOperation } from './operations/end_sessions';
 import { executeOperation } from './operations/execute_operation';
 import type { ReadConcern, ReadConcernLevel, ReadConcernLike } from './read_concern';
 import { ReadPreference, type ReadPreferenceMode } from './read_preference';
+import { type Runtime, type RuntimeAdapters } from './runtime_adapters';
 import type { ServerMonitoringMode } from './sdam/monitor';
 import type { TagSet } from './sdam/server_description';
 import { DeprioritizedServers, readPreferenceServerSelector } from './sdam/server_selection';
@@ -318,6 +319,12 @@ export interface MongoClientOptions extends BSONSerializeOptions, SupportedNodeC
   connectionType?: typeof Connection;
   /** @internal */
   __skipPingOnConnect?: boolean;
+  /**
+   * @experimental
+   *
+   * If provided, any adapters provided will be used in place of the corresponding Node.js module.
+   */
+  runtimeAdapters?: RuntimeAdapters;
 }
 
 /** @public */
@@ -1152,4 +1159,7 @@ export interface MongoOptions
   timeoutMS?: number;
   /** @internal */
   __skipPingOnConnect?: boolean;
+
+  /** @internal */
+  runtime: Runtime;
 }
diff --git a/src/runtime_adapters.ts b/src/runtime_adapters.ts
new file mode 100644
index 00000000000..bb998d4bd09
--- /dev/null
+++ b/src/runtime_adapters.ts
@@ -0,0 +1,49 @@
+/* eslint-disable no-restricted-imports, @typescript-eslint/no-require-imports */
+
+// We squash the restricted import errors here because we are using type-only imports, which
+// do not impact the driver's actual runtime dependencies.
+// We also allow restricted imports in this file, because we expect this file to be the only place actually importing restricted Node APIs.
+
+import type * as os from 'os';
+
+import { type MongoClientOptions } from './mongo_client';
+
+/**
+ * @public
+ * @experimental
+ *
+ * Represents the set of dependencies that the driver uses from the [Node.js OS module](https://nodejs.org/api/os.html).
+ */
+export type OsAdapter = Pick<typeof os, 'release' | 'platform' | 'arch' | 'type'>;
+
+/**
+ * @public
+ * @experimental
+ *
+ * This type represents the set of dependencies that the driver needs from the Javascript runtime in order to function.
+ */
+export interface RuntimeAdapters {
+  os?: OsAdapter;
+}
+
+/**
+ * @internal
+ *
+ * Represents a complete, parsed set of runtime adapters.  After options parsing, all adapters
+ * are always present (either using the user's provided adapter, or defaulting to the Node.js module).
+ */
+export interface Runtime {
+  os: OsAdapter;
+}
+
+/**
+ * @internal
+ *
+ * Given a MongoClientOptions, this function resolves the set of runtime options, providing Nodejs implementations if
+ * not provided by in `options`, and returns a `Runtime`.
+ */
+export function resolveRuntimeAdapters(options: MongoClientOptions): Runtime {
+  return {
+    os: options.runtimeAdapters?.os ?? require('os')
+  };
+}
diff --git a/test/integration/connection-monitoring-and-pooling/connection.test.ts b/test/integration/connection-monitoring-and-pooling/connection.test.ts
index a20f36c7b6e..b6aaf759691 100644
--- a/test/integration/connection-monitoring-and-pooling/connection.test.ts
+++ b/test/integration/connection-monitoring-and-pooling/connection.test.ts
@@ -22,7 +22,7 @@ import { LEGACY_HELLO_COMMAND } from '../../../src/constants';
 import { Topology } from '../../../src/sdam/topology';
 import { HostAddress, ns } from '../../../src/utils';
 import * as mock from '../../tools/mongodb-mock/index';
-import { processTick, sleep } from '../../tools/utils';
+import { processTick, runtime, sleep } from '../../tools/utils';
 import { assert as test, setupDatabase } from '../shared';
 
 const commonConnectOptions = {
@@ -49,7 +49,10 @@ describe('Connection', function () {
           ...commonConnectOptions,
           connectionType: Connection,
           ...this.configuration.options,
-          metadata: makeClientMetadata([], {})
+          metadata: makeClientMetadata([], {
+            runtime
+          }),
+          runtime
         };
 
         let conn;
@@ -71,7 +74,8 @@ describe('Connection', function () {
           connectionType: Connection,
           ...this.configuration.options,
           monitorCommands: true,
-          metadata: makeClientMetadata([], {})
+          runtime,
+          metadata: makeClientMetadata([], { runtime })
         };
 
         let conn;
@@ -102,7 +106,10 @@ describe('Connection', function () {
           connectionType: Connection,
           ...this.configuration.options,
           monitorCommands: true,
-          metadata: makeClientMetadata([], {})
+          runtime,
+          metadata: makeClientMetadata([], {
+            runtime
+          })
         };
 
         let conn;
diff --git a/test/tools/utils.ts b/test/tools/utils.ts
index 5a23fdd9706..d3948d773cd 100644
--- a/test/tools/utils.ts
+++ b/test/tools/utils.ts
@@ -18,10 +18,12 @@ import {
   type HostAddress,
   MongoClient,
   type MongoClientOptions,
+  type Runtime,
   type ServerApiVersion,
   type TopologyOptions
 } from '../../src';
 import { OP_MSG } from '../../src/cmap/wire_protocol/constants';
+import { resolveRuntimeAdapters } from '../../src/runtime_adapters';
 import { Topology } from '../../src/sdam/topology';
 import { processTimeMS } from '../../src/utils';
 import { type TestConfiguration } from './runner/config';
@@ -604,3 +606,8 @@ export function configureMongocryptdSpawnHooks(
     port
   };
 }
+
+/**
+ * A `Runtime` that resolves to entirely Nodejs modules, useful when tests must provide a default `runtime` object to an API.
+ */
+export const runtime: Runtime = resolveRuntimeAdapters({});
diff --git a/test/unit/assorted/optional_require.test.ts b/test/unit/assorted/optional_require.test.ts
index 5dc579ee304..463f7f95ffb 100644
--- a/test/unit/assorted/optional_require.test.ts
+++ b/test/unit/assorted/optional_require.test.ts
@@ -7,6 +7,7 @@ import { GSSAPI } from '../../../src/cmap/auth/gssapi';
 import { compress } from '../../../src/cmap/wire_protocol/compression';
 import { MongoMissingDependencyError } from '../../../src/error';
 import { HostAddress } from '../../../src/utils';
+import { runtime } from '../../tools/utils';
 
 function moduleExistsSync(moduleName) {
   return existsSync(resolve(__dirname, `../../../node_modules/${moduleName}`));
@@ -41,7 +42,13 @@ describe('optionalRequire', function () {
       const gssapi = new GSSAPI();
 
       const error = await gssapi
-        .auth(new AuthContext(null, true, { hostAddress: new HostAddress('a'), credentials: true }))
+        .auth(
+          new AuthContext(null, true, {
+            hostAddress: new HostAddress('a'),
+            credentials: true,
+            runtime
+          })
+        )
         .then(
           () => null,
           e => e
diff --git a/test/unit/cmap/connect.test.ts b/test/unit/cmap/connect.test.ts
index a97cb7194a6..cd205de976c 100644
--- a/test/unit/cmap/connect.test.ts
+++ b/test/unit/cmap/connect.test.ts
@@ -15,6 +15,7 @@ import { CancellationToken } from '../../../src/mongo_types';
 import { HostAddress, isHello } from '../../../src/utils';
 import { genClusterTime } from '../../tools/common';
 import * as mock from '../../tools/mongodb-mock/index';
+import { runtime } from '../../tools/utils';
 
 const CONNECT_DEFAULTS = {
   id: 1,
@@ -210,7 +211,9 @@ describe('Connect Tests', function () {
             connection: {},
             options: {
               ...CONNECT_DEFAULTS,
-              metadata: makeClientMetadata([], {})
+              metadata: makeClientMetadata([], {
+                runtime
+              })
             }
           };
         });
@@ -239,7 +242,10 @@ describe('Connect Tests', function () {
                   name: 's'.repeat(128)
                 }
               ],
-              { appName: longAppName }
+              {
+                appName: longAppName,
+                runtime
+              }
             );
             const longAuthContext = {
               connection: {},
@@ -267,7 +273,9 @@ describe('Connect Tests', function () {
             connection: {},
             options: {
               ...CONNECT_DEFAULTS,
-              metadata: makeClientMetadata([], {})
+              metadata: makeClientMetadata([], {
+                runtime
+              })
             }
           };
         });
@@ -296,7 +304,10 @@ describe('Connect Tests', function () {
                   name: 's'.repeat(128)
                 }
               ],
-              { appName: longAppName }
+              {
+                appName: longAppName,
+                runtime
+              }
             );
             const longAuthContext = {
               connection: {},
diff --git a/test/unit/cmap/handshake/client_metadata.test.ts b/test/unit/cmap/handshake/client_metadata.test.ts
index 61288384481..a7c5e864d7e 100644
--- a/test/unit/cmap/handshake/client_metadata.test.ts
+++ b/test/unit/cmap/handshake/client_metadata.test.ts
@@ -12,6 +12,7 @@ import {
   makeClientMetadata
 } from '../../../../src/cmap/handshake/client_metadata';
 import { MongoInvalidArgumentError } from '../../../../src/error';
+import { runtime } from '../../../tools/utils';
 
 describe('client metadata module', () => {
   afterEach(() => sinon.restore());
@@ -141,7 +142,7 @@ describe('client metadata module', () => {
   describe('makeClientMetadata()', () => {
     context('when no FAAS environment is detected', () => {
       it('does not append FAAS metadata', async () => {
-        const metadata = await makeClientMetadata([], {});
+        const metadata = await makeClientMetadata([], { runtime });
         expect(metadata).not.to.have.property(
           'env',
           'faas metadata applied in a non-faas environment'
@@ -164,14 +165,16 @@ describe('client metadata module', () => {
 
     context('when driverInfo.platform is provided', () => {
       it('throws an error if driverInfo.platform is too large', async () => {
-        const error = await makeClientMetadata([{ platform: 'a'.repeat(512) }], {}).catch(e => e);
+        const error = await makeClientMetadata([{ platform: 'a'.repeat(512) }], { runtime }).catch(
+          e => e
+        );
         expect(error)
           .to.be.instanceOf(MongoInvalidArgumentError)
           .to.match(/platform/);
       });
 
       it('appends driverInfo.platform to the platform field', async () => {
-        const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], {});
+        const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], { runtime });
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs',
@@ -190,12 +193,14 @@ describe('client metadata module', () => {
 
     context('when driverInfo.name is provided', () => {
       it('throws an error if driverInfo.name is too large', async () => {
-        const error = await makeClientMetadata([{ name: 'a'.repeat(512) }], {}).catch(e => e);
+        const error = await makeClientMetadata([{ name: 'a'.repeat(512) }], { runtime }).catch(
+          e => e
+        );
         expect(error).to.be.instanceOf(MongoInvalidArgumentError).to.match(/name/);
       });
 
       it('appends driverInfo.name to the driver.name field', async () => {
-        const metadata = await makeClientMetadata([{ name: 'myName' }], {});
+        const metadata = await makeClientMetadata([{ name: 'myName' }], { runtime });
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs|myName',
@@ -214,14 +219,16 @@ describe('client metadata module', () => {
 
     context('when driverInfo.version is provided', () => {
       it('throws an error if driverInfo.version is too large', async () => {
-        const error = await makeClientMetadata([{ version: 'a'.repeat(512) }], {}).catch(e => e);
+        const error = await makeClientMetadata([{ version: 'a'.repeat(512) }], { runtime }).catch(
+          e => e
+        );
         expect(error)
           .to.be.instanceOf(MongoInvalidArgumentError)
           .to.match(/version/);
       });
 
       it('appends driverInfo.version to the version field', async () => {
-        const metadata = await makeClientMetadata([{ version: 'myVersion' }], {});
+        const metadata = await makeClientMetadata([{ version: 'myVersion' }], { runtime });
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs',
@@ -240,7 +247,7 @@ describe('client metadata module', () => {
 
     context('when no custom driverInto is provided', () => {
       it('does not append the driver info to the metadata', async () => {
-        const metadata = await makeClientMetadata([], {});
+        const metadata = await makeClientMetadata([], { runtime });
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs',
@@ -257,7 +264,7 @@ describe('client metadata module', () => {
       });
 
       it('does not set the application field', async () => {
-        const metadata = await makeClientMetadata([], {});
+        const metadata = await makeClientMetadata([], { runtime });
         expect(metadata).not.to.have.property('application');
       });
     });
@@ -267,6 +274,7 @@ describe('client metadata module', () => {
         it('truncates the application name to <=128 bytes', async () => {
           const longString = 'a'.repeat(300);
           const metadata = await makeClientMetadata([], {
+            runtime,
             appName: longString
           });
           expect(metadata.application?.name).to.be.a('string');
@@ -283,6 +291,7 @@ describe('client metadata module', () => {
           it('truncates the application name to 129 bytes', async () => {
             const longString = '€'.repeat(300);
             const metadata = await makeClientMetadata([], {
+              runtime,
               appName: longString
             });
 
@@ -298,6 +307,7 @@ describe('client metadata module', () => {
       context('when the app name is under 128 bytes', () => {
         it('sets the application name to the value', async () => {
           const metadata = await makeClientMetadata([], {
+            runtime,
             appName: 'myApplication'
           });
           expect(metadata.application?.name).to.equal('myApplication');
@@ -313,37 +323,37 @@ describe('client metadata module', () => {
 
         it('sets platform to Deno', async () => {
           globalThis.Deno = { version: { deno: '1.2.3' } };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Deno v1.2.3, LE');
         });
 
         it('sets platform to Deno with driverInfo.platform', async () => {
           globalThis.Deno = { version: { deno: '1.2.3' } };
-          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], {});
+          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], { runtime });
           expect(metadata.platform).to.equal('Deno v1.2.3, LE|myPlatform');
         });
 
         it('ignores version if Deno.version.deno is not a string', async () => {
           globalThis.Deno = { version: { deno: 1 } };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno.version does not have a deno property', async () => {
           globalThis.Deno = { version: { somethingElse: '1.2.3' } };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno.version is null', async () => {
           globalThis.Deno = { version: null };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno is nullish', async () => {
           globalThis.Deno = null;
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
       });
@@ -357,7 +367,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = '1.2.3';
           };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Bun v1.2.3, LE');
         });
 
@@ -365,7 +375,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = '1.2.3';
           };
-          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], {});
+          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], { runtime });
           expect(metadata.platform).to.equal('Bun v1.2.3, LE|myPlatform');
         });
 
@@ -373,7 +383,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = 1;
           };
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE');
         });
 
@@ -381,13 +391,13 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = 1;
           };
-          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], {});
+          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], { runtime });
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE|myPlatform');
         });
 
         it('ignores version if Bun is nullish', async () => {
           globalThis.Bun = null;
-          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], {});
+          const metadata = await makeClientMetadata([{ platform: 'myPlatform' }], { runtime });
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE|myPlatform');
         });
       });
@@ -508,7 +518,7 @@ describe('client metadata module', () => {
           });
 
           it(`returns ${inspect(outcome)} under env property`, async () => {
-            const { env } = await makeClientMetadata([], {});
+            const { env } = await makeClientMetadata([], { runtime });
             expect(env).to.deep.equal(outcome);
           });
 
@@ -532,7 +542,9 @@ describe('client metadata module', () => {
       });
 
       it('does not attach it to the metadata', async () => {
-        expect(await makeClientMetadata([], {})).not.to.have.nested.property('aws.memory_mb');
+        expect(await makeClientMetadata([], { runtime })).not.to.have.nested.property(
+          'aws.memory_mb'
+        );
       });
     });
   });
@@ -547,7 +559,7 @@ describe('client metadata module', () => {
       });
 
       it('only includes env.name', async () => {
-        const metadata = await makeClientMetadata([], {});
+        const metadata = await makeClientMetadata([], { runtime });
         expect(metadata).to.not.have.nested.property('env.region');
         expect(metadata).to.have.nested.property('env.name', 'aws.lambda');
         expect(metadata.env).to.have.all.keys('name');
@@ -565,7 +577,7 @@ describe('client metadata module', () => {
         });
 
         it('only includes env.name', async () => {
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata).to.have.property('env');
           expect(metadata).to.have.nested.property('env.region', 'abc');
           expect(metadata.os).to.have.all.keys('type');
@@ -582,7 +594,7 @@ describe('client metadata module', () => {
         });
 
         it('omits os information', async () => {
-          const metadata = await makeClientMetadata([], {});
+          const metadata = await makeClientMetadata([], { runtime });
           expect(metadata).to.not.have.property('os');
         });
       });
@@ -598,7 +610,7 @@ describe('client metadata module', () => {
       });
 
       it('omits the faas env', async () => {
-        const metadata = await makeClientMetadata([{ name: 'a'.repeat(350) }], {});
+        const metadata = await makeClientMetadata([{ name: 'a'.repeat(350) }], { runtime });
         expect(metadata).to.not.have.property('env');
       });
     });
diff --git a/test/unit/runtime_adapters.test.ts b/test/unit/runtime_adapters.test.ts
new file mode 100644
index 00000000000..3980f9f1d71
--- /dev/null
+++ b/test/unit/runtime_adapters.test.ts
@@ -0,0 +1,31 @@
+import { expect } from 'chai';
+import * as os from 'os';
+
+import { MongoClient, type OsAdapter } from '../../src';
+
+describe('Runtime Adapters tests', function () {
+  describe('`os`', function () {
+    describe('when no os adapter is provided', function () {
+      it(`defaults to Node's os module`, function () {
+        const client = new MongoClient('mongodb://localhost:27017');
+
+        expect(client.options.runtime.os).to.equal(os);
+      });
+    });
+
+    describe('when an os adapter is provided', function () {
+      it(`uses the user provided adapter`, function () {
+        const osAdapter: OsAdapter = {
+          ...os
+        };
+        const client = new MongoClient('mongodb://localhost:27017', {
+          runtimeAdapters: {
+            os: osAdapter
+          }
+        });
+
+        expect(client.options.runtime.os).to.equal(osAdapter);
+      });
+    });
+  });
+});
diff --git a/test/unit/sdam/topology.test.ts b/test/unit/sdam/topology.test.ts
index 1444e1a40c4..8db64288bd9 100644
--- a/test/unit/sdam/topology.test.ts
+++ b/test/unit/sdam/topology.test.ts
@@ -28,7 +28,7 @@ import { TopologyDescription } from '../../../src/sdam/topology_description';
 import { TimeoutContext } from '../../../src/timeout';
 import { isHello, ns } from '../../../src/utils';
 import * as mock from '../../tools/mongodb-mock/index';
-import { topologyWithPlaceholderClient } from '../../tools/utils';
+import { runtime, topologyWithPlaceholderClient } from '../../tools/utils';
 
 describe('Topology (unit)', function () {
   let client, topology;
@@ -56,6 +56,7 @@ describe('Topology (unit)', function () {
     it('should correctly pass appname', async function () {
       const topology: Topology = topologyWithPlaceholderClient([`localhost:27017`], {
         metadata: makeClientMetadata([], {
+          runtime,
           appName: 'My application name'
         })
       });