diff --git a/block.c b/block.c
index 6af5f6e..53cc9e0 100644
--- a/block.c
+++ b/block.c
@@ -1040,8 +1040,12 @@
         error_free(local_err);
         return ret;
     }
-    pstrcpy(bs->backing_file, sizeof(bs->backing_file),
-            bs->backing_hd->file->filename);
+
+    if (bs->backing_hd->file) {
+        pstrcpy(bs->backing_file, sizeof(bs->backing_file),
+                bs->backing_hd->file->filename);
+    }
+
     return 0;
 }