diff --git a/storage/remote/googleiam/googleiam.go b/storage/remote/googleiam/googleiam.go
index 0ca7185ab7..2095ee9747 100644
--- a/storage/remote/googleiam/googleiam.go
+++ b/storage/remote/googleiam/googleiam.go
@@ -19,7 +19,6 @@ import (
 	"context"
 	"fmt"
 	"net/http"
-	"os"
 
 	"golang.org/x/oauth2/google"
 	"google.golang.org/api/option"
@@ -42,15 +41,7 @@ func NewRoundTripper(cfg *Config, next http.RoundTripper) (http.RoundTripper, er
 		option.WithScopes(scopes),
 	}
 	if cfg.CredentialsFile != "" {
-		credBytes, err := os.ReadFile(cfg.CredentialsFile)
-		if err != nil {
-			return nil, fmt.Errorf("error reading Google credentials file: %w", err)
-		}
-		creds, err := google.CredentialsFromJSON(ctx, credBytes, scopes)
-		if err != nil {
-			return nil, fmt.Errorf("error parsing Google credentials file: %w", err)
-		}
-		opts = append(opts, option.WithCredentials(creds))
+		opts = append(opts, option.WithAuthCredentialsFile(option.ServiceAccount, cfg.CredentialsFile))
 	} else {
 		creds, err := google.FindDefaultCredentials(ctx, scopes)
 		if err != nil {