diff --git a/client/driver/docker.go b/client/driver/docker.go
index 0dacbac10..3d9a418ea 100644
--- a/client/driver/docker.go
+++ b/client/driver/docker.go
@@ -181,11 +181,11 @@ func NewDockerDriverConfig(task *structs.Task, env *env.TaskEnvironment) (*Docke
 		}
 	}
 
-	for _, a := range dconf.Auth {
-		a.Username = env.ReplaceEnv(a.Username)
-		a.Password = env.ReplaceEnv(a.Password)
-		a.Email = env.ReplaceEnv(a.Email)
-		a.ServerAddress = env.ReplaceEnv(a.ServerAddress)
+	for i, a := range dconf.Auth {
+		dconf.Auth[i].Username = env.ReplaceEnv(a.Username)
+		dconf.Auth[i].Password = env.ReplaceEnv(a.Password)
+		dconf.Auth[i].Email = env.ReplaceEnv(a.Email)
+		dconf.Auth[i].ServerAddress = env.ReplaceEnv(a.ServerAddress)
 	}
 
 	for _, l := range dconf.Logging {