diff --git a/llvm/docs/YamlIO.rst b/llvm/docs/YamlIO.rst
index 3cc683b6b820..8b45b6bb85b7 100644
--- a/llvm/docs/YamlIO.rst
+++ b/llvm/docs/YamlIO.rst
@@ -456,10 +456,10 @@ looks like:
 
     template <>
     struct ScalarTraits<MyCustomType> {
-      static void output(const T &value, llvm::raw_ostream &out) {
+      static void output(const T &value, void*, llvm::raw_ostream &out) {
         out << value;  // do custom formatting here
       }
-      static StringRef input(StringRef scalar, T &value) {
+      static StringRef input(StringRef scalar, void*, T &value) {
         // do custom parsing here.  Return the empty string on success,
         // or an error message on failure.
         return StringRef();