diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 3e4ef7e821..d3f7797085 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -696,6 +696,9 @@ struct _qemuBlockNamedNodeData {
 
     qemuBlockNamedNodeDataBitmapPtr *bitmaps;
     size_t nbitmaps;
+
+    /* the cluster size of the image is valid only when > 0 */
+    unsigned long long clusterSize;
 };
 
 virHashTablePtr
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 9cdf6c0f7f..e6d2e7d4db 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -2997,6 +2997,9 @@ qemuMonitorJSONBlockGetNamedNodeDataWorker(size_t pos G_GNUC_UNUSED,
     if (virJSONValueObjectGetNumberUlong(img, "actual-size", &ent->physical) < 0)
         ent->physical = ent->capacity;
 
+    /* try looking up the cluster size */
+    ignore_value(virJSONValueObjectGetNumberUlong(img, "cluster-size", &ent->clusterSize));
+
     if ((bitmaps = virJSONValueObjectGetArray(val, "dirty-bitmaps")))
         qemuMonitorJSONBlockGetNamedNodeDataBitmaps(bitmaps, ent);