diff --git a/core/base/inc/LinkDef.h b/core/base/inc/LinkDef.h
index aa9c55ac74debc0d453ffb3ab986d44efbde05ee..662090c015da940fe6e81196ba074e110d80b9ee 100644
--- a/core/base/inc/LinkDef.h
+++ b/core/base/inc/LinkDef.h
@@ -13,6 +13,8 @@
 #elif defined(SYSTEM_TYPE_macosx)
 #include "core/macosx/inc/LinkDef.h"
 #include "core/unix/inc/LinkDef.h"
-#else
+#elif defined(SYSTEM_TYPE_unix)
 #include "core/unix/inc/LinkDef.h"
+#else
+# error "Unsupported system type."
 #endif