diff --git a/include/llvm/Support/Registry.h b/include/llvm/Support/Registry.h
index 4db88825afb..d0375bedd9f 100644
--- a/include/llvm/Support/Registry.h
+++ b/include/llvm/Support/Registry.h
@@ -203,6 +203,8 @@ namespace llvm {
 
   };
 
+  // Since these are defined in a header file, plugins must be sure to export
+  // these symbols.
 
   template <typename T, typename U>
   typename Registry<T,U>::node *Registry<T,U>::Head;