diff --git a/example/safe_prime.cpp b/example/safe_prime.cpp
index dbe40ef2..ee5e134b 100644
--- a/example/safe_prime.cpp
+++ b/example/safe_prime.cpp
@@ -5,6 +5,7 @@
 
 //[safe_prime
 
+#include <boost/random.hpp>
 #include <boost/multiprecision/cpp_int.hpp>
 #include <boost/multiprecision/miller_rabin.hpp>
 #include <iostream>