diff --git a/block/qcow.c b/block/qcow.c
index 95ab123..7bd94dc 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -852,6 +852,7 @@
             header_size += backing_filename_len;
         } else {
             /* special backing file for vvfat */
+            g_free(backing_file);
             backing_file = NULL;
         }
         header.cluster_bits = 9; /* 512 byte cluster to avoid copying