storage/mmap.go | 4 +++-

diff --git a/storage/mmap.go b/storage/mmap.go
index 94603a8c436110ca6b56ff0700f481019b18d6d8..fec9d117495dbbf6cb8a5b6f4fee8fdc9157567f 100644
--- a/storage/mmap.go
+++ b/storage/mmap.go
@@ -105,7 +105,9 @@ 		if err != nil {
 			err = fmt.Errorf("file %q: %s", miFile.DisplayPath(md), err)
 			return
 		}
-		mms.Append(mm)
+		if mm != nil {
+			mms.Append(mm)
+		}
 	}
 	return
 }