diff --git a/src/util/storage_file.c b/src/util/storage_file.c
index f33ea74a929e6757e63b01f8d2c4f543132c6acf..ba9cfc51c9063dfe9657f4e7dc87c446197282b6 100644
--- a/src/util/storage_file.c
+++ b/src/util/storage_file.c
@@ -333,7 +333,7 @@ qcowXGetBackingStore(char **res,
      * between the end of the header (QCOW2_HDR_TOTAL_SIZE)
      * and the start of the backingStoreName (offset)
      */
-    if (isQCow2)
+    if (isQCow2 && format)
         qcow2GetBackingStoreFormat(format, buf, buf_size, QCOW2_HDR_TOTAL_SIZE, offset);
 
     return BACKING_STORE_OK;