diff --git a/ocw/lib/ec2.py b/ocw/lib/ec2.py
index 2bfb106c..69e06276 100644
--- a/ocw/lib/ec2.py
+++ b/ocw/lib/ec2.py
@@ -176,7 +176,7 @@ def delete_vpc_subnets(self, vpc) -> None:
                     try:
                         interface.delete()
                     except ClientError as exc:
-                        self.log_err("delete_vpc_subnets: %s", exc)
+                        self.log_err("delete_vpc_subnets: {}", exc)
                         continue
             if self.dry_run:
                 self.log_info(f'Deletion of {subnet} skipped due to dry_run mode')
diff --git a/ocw/lib/gce.py b/ocw/lib/gce.py
index abd4cf30..786098ff 100644
--- a/ocw/lib/gce.py
+++ b/ocw/lib/gce.py
@@ -100,7 +100,7 @@ def list_zones(self, region) -> list:
             )
             return [basename(z) for z in region["zones"]]
         except (KeyError, HttpError) as exc:
-            self.log_err("list_zones: %s", exc)
+            self.log_err("list_zones: {}", exc)
             return []
 
     def delete_instance(self, instance_id, zone) -> None: