diff --git a/gtk/FreeSpaceLabel.cc b/gtk/FreeSpaceLabel.cc
index 1b8c82959..83db14085 100644
--- a/gtk/FreeSpaceLabel.cc
+++ b/gtk/FreeSpaceLabel.cc
@@ -54,7 +54,7 @@ bool FreeSpaceLabel::Impl::on_freespace_timer()
     }
 
     auto ec = std::error_code{};
-    auto const capacity = std::filesystem::space(dir_, ec);
+    auto const capacity = std::filesystem::space(tr_u8path(dir_), ec);
     auto const text = !ec ?
         fmt::format(fmt::runtime(_("{disk_space} free")), fmt::arg("disk_space", tr_strlsize(capacity.available))) :
         _("Error");
diff --git a/libtransmission/file.h b/libtransmission/file.h
index 7dfd06098..bf18be751 100644
--- a/libtransmission/file.h
+++ b/libtransmission/file.h
@@ -7,8 +7,10 @@
 
 #include <cstdint> // uint64_t
 #include <ctime> // time_t
+#include <filesystem>
 #include <functional>
 #include <optional>
+#include <ranges>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -508,3 +510,25 @@ bool tr_sys_dir_close(tr_sys_dir_t handle, tr_error* error = nullptr);
 
 /** @} */
 /** @} */
+
+/**
+ * Temporary replacement of deprecated `std::filesystem::u8path()` while we migrate
+ * from char to char8_t strings.
+ *
+ * https://stackoverflow.com/a/57635139/11390656
+ * @{
+ */
+
+template<typename InputIt>
+[[nodiscard]] std::filesystem::path tr_u8path(InputIt begin, InputIt end)
+{
+    auto const view = std::ranges::subrange(begin, end) | std::views::transform([](char const c) -> char8_t { return c; });
+    return { view.begin(), view.end() };
+}
+
+[[nodiscard]] inline std::filesystem::path tr_u8path(std::string_view path)
+{
+    return tr_u8path(path.begin(), path.end());
+}
+
+/// @}
diff --git a/libtransmission/rpcimpl.cc b/libtransmission/rpcimpl.cc
index 98847f293..9b3993f8e 100644
--- a/libtransmission/rpcimpl.cc
+++ b/libtransmission/rpcimpl.cc
@@ -2232,7 +2232,7 @@ using SessionAccessors = std::pair<SessionGetter, SessionSetter>;
         [](tr_session const& src) -> tr_variant
         {
             auto ec = std::error_code{};
-            auto const space = std::filesystem::space(src.downloadDir(), ec);
+            auto const space = std::filesystem::space(tr_u8path(src.downloadDir()), ec);
             return !ec ? space.available : tr_variant{ -1 };
         },
         nullptr);
@@ -2737,7 +2737,7 @@ using SessionAccessors = std::pair<SessionGetter, SessionSetter>;
 
     // get the free space
     auto ec = std::error_code{};
-    auto const capacity = std::filesystem::space(*path, ec);
+    auto const capacity = std::filesystem::space(tr_u8path(*path), ec);
 
     // response
     args_out.try_emplace(TR_KEY_path, *path);