diff --git a/lib/_http_client.js b/lib/_http_client.js
index e8285fe81012c7..3ba986cf6fcfb0 100644
--- a/lib/_http_client.js
+++ b/lib/_http_client.js
@@ -68,9 +68,9 @@ function ClientRequest(options, cb) {
     }
     // Explicitly pass through this statement as agent will not be used
     // when createConnection is provided.
-  } else if (!(agent instanceof Agent.Agent)) {
+  } else if (typeof agent.addRequest !== 'function') {
     throw new TypeError(
-      'Agent option must be an instance of http.Agent, undefined or false.'
+      'Agent option must be an Agent-like object, undefined, or false.'
     );
   }
   self.agent = agent;
diff --git a/test/parallel/test-http-client-reject-unexpected-agent.js b/test/parallel/test-http-client-reject-unexpected-agent.js
index 559166ec421ea2..e89bcfad5b5995 100644
--- a/test/parallel/test-http-client-reject-unexpected-agent.js
+++ b/test/parallel/test-http-client-reject-unexpected-agent.js
@@ -49,7 +49,7 @@ server.listen(0, baseOptions.host, common.mustCall(function() {
   failingAgentOptions.forEach((agent) => {
     assert.throws(
       () => createRequest(agent),
-      /^TypeError: Agent option must be an instance of http.Agent/,
+      /^TypeError: Agent option must be an Agent-like object/,
       `Expected typeof agent: ${typeof agent} to be rejected`
     );
   });