diff --git a/billing/calculate_billing.py b/billing/calculate_billing.py
index 6c24eebe..b4e7f773 100644
--- a/billing/calculate_billing.py
+++ b/billing/calculate_billing.py
@@ -116,7 +116,7 @@ def summary_stats(yml, contingency, months):
     contingency = float(args.contingency) / 100.0
 
     # Read in billing info
-    with open("hub23_billing.yaml", "r") as stream:
+    with open("hub23_billing.yaml") as stream:
         try:
             billing_info = yaml.safe_load(stream)
         except yaml.YAMLError as exc: