diff --git a/src/allmydata/scripts/admin.py b/src/allmydata/scripts/admin.py
index 57cac39c7..e5b7dca2d 100644
--- a/src/allmydata/scripts/admin.py
+++ b/src/allmydata/scripts/admin.py
@@ -92,7 +92,7 @@ class AddGridManagerCertOptions(BaseOptions):
         try:
             self.certificate_data = parse_grid_manager_data(data)
         except ValueError as e:
-            raise UsageError(
+            raise usage.UsageError(
                 "Error parsing certificate: {}".format(e)
             )
 
diff --git a/src/allmydata/scripts/tahoe_grid_manager.py b/src/allmydata/scripts/tahoe_grid_manager.py
index 67c8b631b..f84f57766 100644
--- a/src/allmydata/scripts/tahoe_grid_manager.py
+++ b/src/allmydata/scripts/tahoe_grid_manager.py
@@ -2,7 +2,6 @@ from __future__ import print_function
 
 import sys
 import json
-import time
 from datetime import datetime, timedelta
 
 from allmydata.scripts.common import BaseOptions
diff --git a/src/allmydata/test/test_grid_manager.py b/src/allmydata/test/test_grid_manager.py
index d5c98f2e7..a60739634 100644
--- a/src/allmydata/test/test_grid_manager.py
+++ b/src/allmydata/test/test_grid_manager.py
@@ -2,7 +2,6 @@
 import json
 
 from allmydata.client import (
-    _load_grid_manager_certificates,
     create_storage_farm_broker,
 )
 from allmydata.node import (