diff --git a/api/organisations/subscriptions/licensing/helpers.py b/api/organisations/subscriptions/licensing/helpers.py
index b86687753985..9cf8e2eb65ef 100644
--- a/api/organisations/subscriptions/licensing/helpers.py
+++ b/api/organisations/subscriptions/licensing/helpers.py
@@ -9,9 +9,16 @@
 logger: logging.Logger = logging.getLogger(name=__name__)
 
 
+class PrivateKeyMissingError(RuntimeError):
+    pass
+
+
 def sign_licence(licence: str) -> str:
     message = licence.encode("utf-8")
 
+    if not settings.SUBSCRIPTION_LICENCE_PRIVATE_KEY:
+        raise PrivateKeyMissingError("Private key is missing")
+
     # Load the private key from PEM
     private_key = serialization.load_pem_private_key(
         settings.SUBSCRIPTION_LICENCE_PRIVATE_KEY.encode("utf-8"), password=None