diff --git a/deno.json b/deno.json
index 4ec27cd..52ed44e 100644
--- a/deno.json
+++ b/deno.json
@@ -14,13 +14,13 @@
     ]
   },
   "tasks": {
-    "proxy:start": "deno run --allow-env --allow-read --allow-sys --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,localhost src/proxy.ts",
-    "proxy:watch": "deno run --watch --allow-env --allow-read --allow-sys --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,localhost src/proxy.ts",
-    "client:start": "deno run --allow-env --allow-read --allow-sys --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,localhost src/client.ts",
-    "client:watch": "deno run --watch --allow-env --allow-read --allow-sys --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,localhost src/client.ts",
-    "test": "deno test --allow-net --allow-env --allow-read tests/",
-    "test:watch": "deno test --watch --allow-net --allow-env --allow-read tests/",
-    "test:coverage": "deno test --coverage=coverage --allow-net --allow-env --allow-read tests/ && deno coverage coverage"
+    "proxy:start": "deno run --allow-env --allow-read --allow-sys=homedir --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,127.0.0.1,localhost src/proxy.ts",
+    "proxy:watch": "deno run --watch --allow-env --allow-read --allow-sys=homedir --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,127.0.0.1,localhost src/proxy.ts",
+    "client:start": "deno run --allow-env --allow-read --allow-sys=homedir --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,127.0.0.1,localhost src/client.ts",
+    "client:watch": "deno run --watch --allow-env --allow-read --allow-sys=homedir --allow-run=open --allow-write=\"$HOME/.mcp-auth/mcp-remote-deno-1.0.0\" --allow-net=0.0.0.0,127.0.0.1,localhost src/client.ts",
+    "test": "deno test --allow-net=0.0.0.0,127.0.0.1,localhost --allow-env --allow-read --allow-sys=homedir tests/",
+    "test:watch": "deno test --watch --allow-net=0.0.0.0,127.0.0.1,localhost --allow-env --allow-read --allow-sys=homedir tests/",
+    "test:coverage": "deno test --coverage=coverage --allow-net=0.0.0.0,127.0.0.1,localhost --allow-env --allow-read --allow-sys=homedir tests/ && deno coverage coverage"
   },
   "imports": {
     "std/": "https://deno.land/std@0.224.0/",
diff --git a/src/lib/coordination.ts b/src/lib/coordination.ts
index d81d3ba..60c28c2 100644
--- a/src/lib/coordination.ts
+++ b/src/lib/coordination.ts
@@ -159,7 +159,7 @@ export async function coordinateAuth(
         log("Authentication completed by another instance");
 
         // Setup a dummy server - the client will use tokens directly from disk
-        const dummyServer = express().listen(0, "localhost"); // Listen on any available port on localhost only
+        const dummyServer = express().listen(0, "127.0.0.1"); // Listen on any available port on localhost only
 
         // This shouldn't actually be called in normal operation, but provide it for API compatibility
         const dummyWaitForAuthCode = () => {
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index 346448f..44b823d 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -247,7 +247,7 @@ export function setupOAuthCallbackServerWithLongPoll(
     options.events.emit("auth-code-received", code);
   });
 
-  const server = app.listen(options.port, "localhost", () => {
+  const server = app.listen(options.port, "127.0.0.1", () => {
     log(`OAuth callback server running at http://127.0.0.1:${options.port}`);
   });
 
@@ -281,7 +281,7 @@ export function findAvailablePort(
     server.on("error", (err: NodeJS.ErrnoException) => {
       if (err.code === "EADDRINUSE") {
         // If preferred port is in use, get a random port
-        server.listen({ port: 0, hostname: "localhost" });
+        server.listen({ port: 0, hostname: "127.0.0.1" });
       } else {
         reject(err);
       }
@@ -295,7 +295,7 @@ export function findAvailablePort(
     });
 
     // Try preferred port first, or get a random port
-    server.listen({ port: preferredPort || 0, hostname: "localhost" });
+    server.listen({ port: preferredPort || 0, hostname: "127.0.0.1" });
   });
 }
 
diff --git a/tests/deno-http-server_test.ts b/tests/deno-http-server_test.ts
index becd256..9c78fa8 100644
--- a/tests/deno-http-server_test.ts
+++ b/tests/deno-http-server_test.ts
@@ -76,9 +76,9 @@ describe("DenoHttpServer", () => {
 
     try {
       serverInstance = server.listen(localTestPort, "localhost");
-      // Use the port property directly - we know our implementation returns an object with port
-      const port = (serverInstance as unknown as { port: number }).port;
-      assertEquals(port, localTestPort);
+      // Our implementation returns an object with address() that returns {port}
+      const addr = serverInstance.address() as { port: number };
+      assertEquals(localTestPort, addr.port);
     } finally {
       if (serverInstance) {
         server.close();