diff --git a/tests/utils/start-prism.sh b/tests/utils/start-prism.sh
index 7a29b941..5beefe56 100755
--- a/tests/utils/start-prism.sh
+++ b/tests/utils/start-prism.sh
@@ -1,11 +1,11 @@
 #!/bin/bash
 
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero_accounting.yaml --host 127.0.0.1 --port 4010 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-app-store.yaml --host 127.0.0.1 --port 4011 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero_assets.yaml --host 127.0.0.1 --port 4012 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero_bankfeeds.yaml --host 127.0.0.1 --port 4013 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-finance.yaml --host 127.0.0.1 --port 4014 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-payroll-uk.yaml --host 127.0.0.1 --port 4015 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-payroll-nz.yaml --host 127.0.0.1 --port 4016 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-payroll-au.yaml --host 127.0.0.1 --port 4017 &
-prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/master/xero-projects.yaml --host 127.0.0.1 --port 4018
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero_accounting.yaml --host 127.0.0.1 --port 4010 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-app-store.yaml --host 127.0.0.1 --port 4011 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero_assets.yaml --host 127.0.0.1 --port 4012 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero_bankfeeds.yaml --host 127.0.0.1 --port 4013 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-finance.yaml --host 127.0.0.1 --port 4014 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-payroll-uk.yaml --host 127.0.0.1 --port 4015 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-payroll-nz.yaml --host 127.0.0.1 --port 4016 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-payroll-au.yaml --host 127.0.0.1 --port 4017 &
+prism mock https://raw.githubusercontent.com/XeroAPI/Xero-OpenAPI/refs/heads/$1/xero-projects.yaml --host 127.0.0.1 --port 4018