diff --git a/example/doc_clone_ptr.cpp b/example/doc_clone_ptr.cpp
index f1b72b0..8842e38 100644
--- a/example/doc_clone_ptr.cpp
+++ b/example/doc_clone_ptr.cpp
@@ -19,15 +19,15 @@ class Base
    public:
    Base(){}
 
-   Base(const Base &x) {/**/}             // Copy ctor
+   Base(const Base &/*x*/) {/**/}            // Copy ctor
 
-   Base(BOOST_RV_REF(Base) x) {/**/}      // Move ctor
+   Base(BOOST_RV_REF(Base) /*x*/) {/**/}     // Move ctor
 
-   Base& operator=(BOOST_RV_REF(Base) x)
-   {/**/ return *this;}                   // Move assign
+   Base& operator=(BOOST_RV_REF(Base) /*x*/)
+   {/**/ return *this;}                      // Move assign
 
-   Base& operator=(BOOST_COPY_ASSIGN_REF(Base) x)
-   {/**/ return *this;}                   // Copy assign
+   Base& operator=(BOOST_COPY_ASSIGN_REF(Base) /*x*/)
+   {/**/ return *this;}                      // Copy assign
    
    virtual Base *clone() const
    {  return new Base(*this);  }