diff --git a/src/nostalgia/player/app.hpp b/src/nostalgia/player/app.hpp
index be97b74a..17df608f 100644
--- a/src/nostalgia/player/app.hpp
+++ b/src/nostalgia/player/app.hpp
@@ -4,4 +4,4 @@
 
 #include <ox/std/memory.hpp>
 
-class ox::Error run(ox::UniquePtr<class ox::FileSystem> fs) noexcept;
+typename ox::Error run(ox::UniquePtr<class ox::FileSystem> fs) noexcept;
diff --git a/src/nostalgia/tools/pack/pack.hpp b/src/nostalgia/tools/pack/pack.hpp
index 8fece55b..09c78495 100644
--- a/src/nostalgia/tools/pack/pack.hpp
+++ b/src/nostalgia/tools/pack/pack.hpp
@@ -4,6 +4,6 @@
 
 namespace nostalgia {
 
-class ox::Error pack(class ox::FileSystem *src, class ox::FileSystem *dest) noexcept;
+typename ox::Error pack(class ox::FileSystem *src, class ox::FileSystem *dest) noexcept;
 
 }