diff --git a/docker-compose.yml b/docker-compose.yml
index 7894b799..29712419 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -19,6 +19,7 @@ services:
       - "8085:8085"
       - "1455:1455"
       - "54545:54545"
+      - "51121:51121"
       - "11451:11451"
     volumes:
       - ./config.yaml:/CLIProxyAPI/config.yaml
diff --git a/sdk/auth/antigravity.go b/sdk/auth/antigravity.go
index 392cc227..84fa4b53 100644
--- a/sdk/auth/antigravity.go
+++ b/sdk/auth/antigravity.go
@@ -21,6 +21,7 @@ import (
 const (
 	antigravityClientID     = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
 	antigravityClientSecret = "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"
+	antigravityCallbackPort = 51121
 )
 
 var antigravityScopes = []string{
@@ -160,7 +161,8 @@ type callbackResult struct {
 }
 
 func startAntigravityCallbackServer() (*http.Server, int, <-chan callbackResult, error) {
-	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	addr := fmt.Sprintf(":%d", antigravityCallbackPort)
+	listener, err := net.Listen("tcp", addr)
 	if err != nil {
 		return nil, 0, nil, err
 	}