diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 7b059908a0ed2778aee175bdaf339db58a0752a0..dff782fc211e4ac2c5aa127d48d849e24d7e7dc3 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -571,15 +571,14 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
         return 0;
     }
 
+    /* Compression can't overwrite anything. Fail if the cluster was already
+     * allocated. */
     cluster_offset = be64_to_cpu(l2_table[l2_index]);
-    if (cluster_offset & QCOW_OFLAG_COPIED) {
+    if (cluster_offset & L2E_OFFSET_MASK) {
         qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
         return 0;
     }
 
-    if (cluster_offset)
-        qcow2_free_any_clusters(bs, cluster_offset, 1);
-
     cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
     if (cluster_offset < 0) {
         qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);