diff --git a/app/notify_client/invite_api_client.py b/app/notify_client/invite_api_client.py
index 1debeaea2..3605cbfa8 100644
--- a/app/notify_client/invite_api_client.py
+++ b/app/notify_client/invite_api_client.py
@@ -32,11 +32,11 @@ class InviteApiClient(NotifyAdminAPIClient):
             "folder_permissions": folder_permissions,
         }
         data = _attach_current_user(data)
-        resp = self.post(url="/service/{}/invite".format(service_id), data=data)
+        resp = self.post(url=f"/service/{service_id}/invite", data=data)
         return resp["data"]
 
     def get_invites_for_service(self, service_id):
-        return self.get("/service/{}/invite".format(service_id))["data"]
+        return self.get(f"/service/{service_id}/invite")["data"]
 
     def get_invited_user(self, invited_user_id):
         return self.get(f"/invite/service/{invited_user_id}")["data"]
@@ -46,7 +46,7 @@ class InviteApiClient(NotifyAdminAPIClient):
 
     def get_count_of_invites_with_permission(self, service_id, permission):
         if permission not in all_ui_permissions:
-            raise TypeError("{} is not a valid permission".format(permission))
+            raise TypeError(f"{permission} is not a valid permission")
         return len(
             [
                 invited_user
@@ -56,13 +56,13 @@ class InviteApiClient(NotifyAdminAPIClient):
         )
 
     def check_token(self, token):
-        return self.get(url="/invite/service/check/{}".format(token))["data"]
+        return self.get(url=f"/invite/service/check/{token}")["data"]
 
     def cancel_invited_user(self, service_id, invited_user_id):
         data = {"status": "cancelled"}
         data = _attach_current_user(data)
         self.post(
-            url="/service/{0}/invite/{1}".format(service_id, invited_user_id), data=data
+            url=f"/service/{service_id}/invite/{invited_user_id}", data=data
         )
 
     @cache.delete("service-{service_id}")
@@ -70,7 +70,7 @@ class InviteApiClient(NotifyAdminAPIClient):
     def accept_invite(self, service_id, invited_user_id):
         data = {"status": "accepted"}
         self.post(
-            url="/service/{0}/invite/{1}".format(service_id, invited_user_id), data=data
+            url=f"/service/{service_id}/invite/{invited_user_id}", data=data
         )