diff --git a/io.hpp b/io.hpp
index 347a67c5..00007e1e 100644
--- a/io.hpp
+++ b/io.hpp
@@ -213,6 +213,12 @@ namespace cruft {
         std::filesystem::path const m_path;
     };
 
+
+    class expected_directory_error : public path_error {
+        using path_error::path_error;
+    };
+
+
     class stream_error : public std::exception {
     public:
         virtual const char* what (void) const noexcept