diff --git a/docs/generated/changelog.html b/docs/generated/changelog.html
index 0aec23b41..3082cfcf9 100644
--- a/docs/generated/changelog.html
+++ b/docs/generated/changelog.html
@@ -11,6 +11,17 @@ <h1>Agent-JS Changelog</h1>
 
     <section>
       <h2>Version x.x.x</h2>
+      <ul>
+        <li></li>
+      </ul>
+      <h2>Version 0.19.2</h2>
+      <ul>
+        <li>
+          fix: subdomains on icp0.io and ic0.app were incorrectly sending requests to icp-api and
+          encountering CSP issues
+        </li>
+      </ul>
+      <h2>Version 0.19.1</h2>
       <ul>
         <li>fix: default host logic fixed and tests added</li>
       </ul>
diff --git a/packages/agent/src/agent/http/http.test.ts b/packages/agent/src/agent/http/http.test.ts
index 3adcda2e1..1df6284c7 100644
--- a/packages/agent/src/agent/http/http.test.ts
+++ b/packages/agent/src/agent/http/http.test.ts
@@ -763,7 +763,6 @@ test('should fetch with given call options and fetch options', async () => {
 describe('default host', () => {
   it('should use a default host of icp-api.io', () => {
     const agent = new HttpAgent({ fetch: jest.fn() });
-    window.location.hostname; //?
     expect((agent as any)._host.hostname).toBe('icp-api.io');
   });
   it('should use a default of icp-api.io if location is not available', () => {
@@ -783,4 +782,32 @@ describe('default host', () => {
       expect((agent as any)._host.hostname).toBe(host);
     }
   });
+  it('should correctly handle subdomains on known hosts', () => {
+    const knownHosts = ['ic0.app', 'icp0.io', 'localhost', '127.0.0.1'];
+    for (const host of knownHosts) {
+      delete window.location;
+      window.location = {
+        host: `foo.${host}`,
+        hostname: `rrkah-fqaaa-aaaaa-aaaaq-cai.${host}`,
+        protocol: 'https:',
+      } as any;
+      const agent = new HttpAgent({ fetch: jest.fn() });
+      expect((agent as any)._host.hostname).toBe(host);
+    }
+  });
+  it('should handle port numbers for localhost', () => {
+    const knownHosts = ['localhost', '127.0.0.1'];
+    for (const host of knownHosts) {
+      delete window.location;
+      // hostname is different from host when port is specified
+      window.location = {
+        host: `${host}:4943`,
+        hostname: `${host}`,
+        protocol: 'http:',
+        port: '4943',
+      } as any;
+      const agent = new HttpAgent({ fetch: jest.fn() });
+      expect((agent as any)._host.hostname).toBe(host);
+    }
+  });
 });
diff --git a/packages/agent/src/agent/http/index.ts b/packages/agent/src/agent/http/index.ts
index d1442f85b..e4b5d1e30 100644
--- a/packages/agent/src/agent/http/index.ts
+++ b/packages/agent/src/agent/http/index.ts
@@ -212,9 +212,17 @@ export class HttpAgent implements Agent {
       }
       // Mainnet and local will have the api route available
       const knownHosts = ['ic0.app', 'icp0.io', 'localhost', '127.0.0.1'];
-      if (location && knownHosts.includes(location.hostname)) {
+      const hostname = location?.hostname;
+      let knownHost;
+      if (hostname && typeof hostname === 'string') {
+        knownHost = knownHosts.find(host => hostname.endsWith(host));
+      }
+
+      if (location && knownHost) {
         // If the user is on a boundary-node provided host, we can use the same host for the agent
-        this._host = new URL(location + '');
+        this._host = new URL(
+          `${location.protocol}//${knownHost}${location.port ? ':' + location.port : ''}`,
+        );
       } else {
         this._host = new URL('https://icp-api.io');
         console.warn(
diff --git a/packages/auth-client/src/index.test.ts b/packages/auth-client/src/index.test.ts
index 56a78e003..4e249d1ba 100644
--- a/packages/auth-client/src/index.test.ts
+++ b/packages/auth-client/src/index.test.ts
@@ -84,6 +84,9 @@ describe('Auth Client', () => {
     (window as any).location = {
       reload: jest.fn(),
       fetch,
+      hostname: 'localhost',
+      protocol: 'http:',
+      port: '4943',
       toString: jest.fn(() => 'http://localhost:4943'),
     };