diff --git a/bundles/postgresql/metadata.py b/bundles/postgresql/metadata.py
index 764c9b8..e0904f2 100644
--- a/bundles/postgresql/metadata.py
+++ b/bundles/postgresql/metadata.py
@@ -20,7 +20,7 @@ defaults = {
         },
         'databases': {},
     },
-    'grafana_rows': {},
+    'grafana_rows': set(),
 }
 
 if node.has_bundle('zfs'):
diff --git a/bundles/telegraf/metadata.py b/bundles/telegraf/metadata.py
index 228d788..f028a1b 100644
--- a/bundles/telegraf/metadata.py
+++ b/bundles/telegraf/metadata.py
@@ -50,12 +50,12 @@ defaults = {
             },
         },
     },
-    'grafana_rows': [
+    'grafana_rows': {
         'cpu',
         'mem',
         'disk_io',
         'net_io',
-    ],
+    },
 }