diff --git a/samples/tasks/scenarios/nova/boot-and-block-migrate.yaml b/samples/tasks/scenarios/nova/boot-and-block-migrate.yaml
index d02508bd..4fb18992 100644
--- a/samples/tasks/scenarios/nova/boot-and-block-migrate.yaml
+++ b/samples/tasks/scenarios/nova/boot-and-block-migrate.yaml
@@ -8,7 +8,7 @@ NovaServers.boot_and_live_migrate_server:
       name: "^cirros.*uec$"
     block_migration: true
   runner:
-    type: constant
+    type: "constant"
     times: 10
     concurrency: 2
   context:
diff --git a/samples/tasks/scenarios/nova/boot-and-live-migrate.yaml b/samples/tasks/scenarios/nova/boot-and-live-migrate.yaml
index 2e468379..1bee05e3 100644
--- a/samples/tasks/scenarios/nova/boot-and-live-migrate.yaml
+++ b/samples/tasks/scenarios/nova/boot-and-live-migrate.yaml
@@ -8,7 +8,7 @@ NovaServers.boot_and_live_migrate_server:
       name: "^cirros.*uec$"
     block_migration: false
   runner:
-    type: constant
+    type: "constant"
     times: 10
     concurrency: 2
   context:
diff --git a/samples/tasks/scenarios/nova/boot-and-migrate.yaml b/samples/tasks/scenarios/nova/boot-and-migrate.yaml
index e53a6301..798bd371 100644
--- a/samples/tasks/scenarios/nova/boot-and-migrate.yaml
+++ b/samples/tasks/scenarios/nova/boot-and-migrate.yaml
@@ -7,7 +7,7 @@ NovaServers.boot_and_migrate_server:
     image:
       name: "^cirros.*uec$"
   runner:
-    type: constant
+    type: "constant"
     times: 10
     concurrency: 2
   context:
diff --git a/samples/tasks/scenarios/nova/boot-and-rebuild.yaml b/samples/tasks/scenarios/nova/boot-and-rebuild.yaml
index 156f7443..e9766e39 100644
--- a/samples/tasks/scenarios/nova/boot-and-rebuild.yaml
+++ b/samples/tasks/scenarios/nova/boot-and-rebuild.yaml
@@ -9,7 +9,7 @@ NovaServers.boot_and_rebuild_server:
     to_image:
       name: "^cirros.*uec$"
   runner:
-    type: constant
+    type: "constant"
     times: 5
     concurrency: 2
   context:
diff --git a/samples/tasks/scenarios/nova/boot-server-attach-created-volume-and-live-migrate.yaml b/samples/tasks/scenarios/nova/boot-server-attach-created-volume-and-live-migrate.yaml
index 0a27d103..3c8bc1da 100644
--- a/samples/tasks/scenarios/nova/boot-server-attach-created-volume-and-live-migrate.yaml
+++ b/samples/tasks/scenarios/nova/boot-server-attach-created-volume-and-live-migrate.yaml
@@ -9,7 +9,7 @@ NovaServers.boot_server_attach_created_volume_and_live_migrate:
     size: 10
     block_migration: false
   runner:
-    type: constant
+    type: "constant"
     times: 5
     concurrency: 1
   context:
diff --git a/samples/tasks/scenarios/nova/boot-server-from-volume-and-live-migrate.yaml b/samples/tasks/scenarios/nova/boot-server-from-volume-and-live-migrate.yaml
index 51979d6f..51d236b4 100644
--- a/samples/tasks/scenarios/nova/boot-server-from-volume-and-live-migrate.yaml
+++ b/samples/tasks/scenarios/nova/boot-server-from-volume-and-live-migrate.yaml
@@ -10,7 +10,7 @@ NovaServers.boot_server_from_volume_and_live_migrate:
     volume_size: 10
     force_delete: false
   runner:
-    type: constant
+    type: "constant"
     times: 10
     concurrency: 2
   context: