diff --git a/block/src/formats/qcow/metadata.rs b/block/src/formats/qcow/metadata.rs
index aa477f1d9..48f67af4b 100644
--- a/block/src/formats/qcow/metadata.rs
+++ b/block/src/formats/qcow/metadata.rs
@@ -954,6 +954,7 @@ impl QcowState {
                 }
                 Ok(Some(freed_cluster)) => {
                     let mut freed = self.set_cluster_refcount(freed_cluster, 0)?;
+                    unref_clusters.push(freed_cluster);
                     unref_clusters.append(&mut freed);
                     refcount_set = true;
                 }