diff --git a/repertory/librepertory/include/file_manager/open_file_base.hpp b/repertory/librepertory/include/file_manager/open_file_base.hpp
index e075ec98..23681bcd 100644
--- a/repertory/librepertory/include/file_manager/open_file_base.hpp
+++ b/repertory/librepertory/include/file_manager/open_file_base.hpp
@@ -131,7 +131,9 @@ private:
 protected:
   [[nodiscard]] auto do_io(std::function<api_error()> action) -> api_error;
 
-  [[nodiscard]] auto get_mutex() const -> std::recursive_mutex &;
+  [[nodiscard]] auto get_mutex() const -> std::recursive_mutex & {
+    return file_mtx_;
+  }
 
   [[nodiscard]] auto get_last_chunk_size() const -> std::size_t;