diff --git a/include/dwarfs/filesystem_v2.h b/include/dwarfs/filesystem_v2.h
index 60972897..71f25697 100644
--- a/include/dwarfs/filesystem_v2.h
+++ b/include/dwarfs/filesystem_v2.h
@@ -55,6 +55,8 @@ class progress;
 
 class filesystem_v2 {
  public:
+  filesystem_v2() = default;
+
   filesystem_v2(logger& lgr, std::shared_ptr<mmif> mm);
 
   filesystem_v2(logger& lgr, std::shared_ptr<mmif> mm,