diff --git a/README.md b/README.md
index 1f91b80..76eeca4 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@ No application is perfect from the beginning. With over a dozen coming articles,
 1. [**Too modern Go application? Building a serverless application with Google Cloud Run and Firebase**](https://threedots.tech/post/serverless-cloud-run-firebase-modern-go-application/?utm_source=github.com)
 2. [**A complete Terraform setup of a serverless application on Google Cloud Run and Firebase**](https://threedots.tech/post/complete-setup-of-serverless-application/?utm_source=github.com)
 3. [**Robust gRPC communication on Google Cloud Run (but not only!)**](https://threedots.tech/post/robust-grpc-google-cloud-run/?utm_source=github.com)
+3. [**You should not build your own authentication. Let Firebase do it for you.**](https://threedots.tech/post/firebase-cloud-run-authentication/?utm_source=github.com)
 4. *More articles are on the way!*
 
 ### Directories
diff --git a/internal/common/server/http.go b/internal/common/server/http.go
index 52f1ae0..4726f09 100644
--- a/internal/common/server/http.go
+++ b/internal/common/server/http.go
@@ -54,7 +54,7 @@ func addAuthMiddleware(router *chi.Mux) {
 
 	var opts []option.ClientOption
 	if file := os.Getenv("SERVICE_ACCOUNT_FILE"); file != "" {
-		opts = append(opts, option.WithCredentialsFile("/service-account-file.json"))
+		opts = append(opts, option.WithCredentialsFile(file))
 	}
 
 	config := &firebase.Config{ProjectID: os.Getenv("GCP_PROJECT")}
diff --git a/internal/users/fixtures.go b/internal/users/fixtures.go
index 7913508..29853ab 100644
--- a/internal/users/fixtures.go
+++ b/internal/users/fixtures.go
@@ -63,7 +63,7 @@ func createFirebaseUsers() ([]string, error) {
 
 	var opts []option.ClientOption
 	if file := os.Getenv("SERVICE_ACCOUNT_FILE"); file != "" {
-		opts = append(opts, option.WithCredentialsFile("/service-account-file.json"))
+		opts = append(opts, option.WithCredentialsFile(file))
 	}
 
 	config := &firebase.Config{ProjectID: os.Getenv("GCP_PROJECT")}