diff --git a/include/boost/random/variate_generator.hpp b/include/boost/random/variate_generator.hpp
index 6d5aac4e4..8252a0550 100644
--- a/include/boost/random/variate_generator.hpp
+++ b/include/boost/random/variate_generator.hpp
@@ -66,7 +66,7 @@ class variate_generator
      * Throws: If and what the copy constructor of Engine or
      * Distribution throws.
      */
-    variate_generator(Engine e, Distribution d)
+    variate_generator(const Engine& e, const Distribution& d)
       : _eng(e), _dist(d) { }
 
     /** Returns: distribution()(engine()) */