diff --git a/source/mijin/util/os.cpp b/source/mijin/util/os.cpp
index 621914f..f3537b9 100644
--- a/source/mijin/util/os.cpp
+++ b/source/mijin/util/os.cpp
@@ -2,7 +2,6 @@
 #include "os.hpp"
 
 #include <filesystem>
-#include "../detect.hpp"
 
 #if MIJIN_TARGET_OS == MIJIN_OS_LINUX
     #include <dlfcn.h>
diff --git a/source/mijin/util/os.hpp b/source/mijin/util/os.hpp
index ec936c7..616ffc5 100644
--- a/source/mijin/util/os.hpp
+++ b/source/mijin/util/os.hpp
@@ -20,6 +20,15 @@ namespace mijin
 // public constants
 //
 
+#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
+inline const std::string_view LIBRARY_EXT = "so";
+#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
+inline const std::string_view LIBRARY_EXT = "dll";
+#else
+[[deprecated("OS not supported.")]]
+inline const int LIBRARY_EXT = 0;
+#endif
+
 //
 // public types
 //