diff --git a/enrollments-events/app/events/issue_cert.py b/enrollments-events/app/events/issue_cert.py
index 6fbf7a5..0cf149a 100644
--- a/enrollments-events/app/events/issue_cert.py
+++ b/enrollments-events/app/events/issue_cert.py
@@ -40,7 +40,12 @@ def lambda_handler(event: EventBridgeEvent, context: LambdaContext) -> bool:
 
     started_at: datetime = fromisoformat(new_image['started_at'])  # type: ignore
     completed_at: datetime = fromisoformat(new_image['completed_at'])  # type: ignore
-    cert_expires_at = completed_at + timedelta(days=int(cert['exp_interval']))
+    # The certificate may not expire
+    cert_expires_at = (
+        completed_at + timedelta(days=int(cert['exp_interval']))
+        if 'exp_interval' in cert
+        else None
+    )
 
     try:
         # Send template URI and data to Paperforge API to generate a PDF
@@ -58,7 +63,12 @@ def lambda_handler(event: EventBridgeEvent, context: LambdaContext) -> bool:
                         'completed_at': completed_at.strftime('%d/%m/%Y'),
                         'today': _datefmt(now_),
                         'year': now_.strftime('%Y'),
-                    },
+                    }
+                    | (
+                        {'expires_at': cert_expires_at.strftime('%d/%m/%Y')}
+                        if cert_expires_at
+                        else {}
+                    ),
                 },
             ),
         )
@@ -93,8 +103,8 @@ def lambda_handler(event: EventBridgeEvent, context: LambdaContext) -> bool:
             ':now': now_,
             ':issued_cert': {
                 'issued_at': now_,
-                'expires_at': cert_expires_at,
             }
+            | ({'expires_at': cert_expires_at} if cert_expires_at else {})
             | ({'s3_uri': s3_uri} if s3_uri else {}),
         },
         cond_expr='attribute_exists(sk)',