diff --git a/packages/opencode/test/mcp/oauth-callback.test.ts b/packages/opencode/test/mcp/oauth-callback.test.ts
index 584b651df0..46531bda18 100644
--- a/packages/opencode/test/mcp/oauth-callback.test.ts
+++ b/packages/opencode/test/mcp/oauth-callback.test.ts
@@ -82,12 +82,13 @@ describe("McpOAuthCallback.ensureRunning", () => {
   })
 
   test("starts server with custom redirectUri port and path", async () => {
-    await McpOAuthCallback.ensureRunning("http://127.0.0.1:18000/custom/callback")
+    const port = await getFreeLoopbackPort()
+    await McpOAuthCallback.ensureRunning(`http://127.0.0.1:${port}/custom/callback`)
     expect(McpOAuthCallback.isRunning()).toBe(true)
   })
 
   test("stops after the callback completes", async () => {
-    const redirectUri = "http://127.0.0.1:18003/custom/callback"
+    const redirectUri = `http://127.0.0.1:${await getFreeLoopbackPort()}/custom/callback`
     await McpOAuthCallback.ensureRunning(redirectUri)
     const callback = McpOAuthCallback.waitForCallback("success")
 
@@ -99,7 +100,7 @@ describe("McpOAuthCallback.ensureRunning", () => {
   })
 
   test("escapes provider error markup in callback HTML", async () => {
-    const redirectUri = "http://127.0.0.1:18001/custom/callback"
+    const redirectUri = `http://127.0.0.1:${await getFreeLoopbackPort()}/custom/callback`
     await McpOAuthCallback.ensureRunning(redirectUri)
 
     const error = `<script>alert("xss" & 'more')</script>`
@@ -114,7 +115,7 @@ describe("McpOAuthCallback.ensureRunning", () => {
   })
 
   test("keeps normal provider errors readable", async () => {
-    const redirectUri = "http://127.0.0.1:18002/custom/callback"
+    const redirectUri = `http://127.0.0.1:${await getFreeLoopbackPort()}/custom/callback`
     await McpOAuthCallback.ensureRunning(redirectUri)
 
     const response = await fetch(