diff --git a/vm-image-spec.yaml b/vm-image-spec.yaml
index 5b93088303..c760744491 100644
--- a/vm-image-spec.yaml
+++ b/vm-image-spec.yaml
@@ -187,6 +187,14 @@ files:
         query: |
           select sum(pg_database_size(datname)) as total from pg_database;
 
+      - metric_name: lfc_approximate_working_set_size
+        type: gauge
+        help: 'Approximate working set size in pages of 8192 bytes'
+        key_labels:
+        values: [approximate_working_set_size]
+        query: |
+          select neon.approximate_working_set_size(false) as approximate_working_set_size;
+
 build: |
   # Build cgroup-tools
   #