diff --git a/nova/compute/api.py b/nova/compute/api.py
index 35a7d7bc02ef..5f68fcc4d749 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -319,12 +319,12 @@ class API(base.Base):
         try:
             instance = self.get(context, instance_id)
         except exception.NotFound:
-            LOG.warning(_("Instance %d was not found during terminate"),
+            LOG.warning(_("Instance %s was not found during terminate"),
                         instance_id)
             raise
 
         if (instance['state_description'] == 'terminating'):
-            LOG.warning(_("Instance %d is already being terminated"),
+            LOG.warning(_("Instance %s is already being terminated"),
                         instance_id)
             return