diff --git a/src/util/digest.cpp b/src/util/digest.cpp
index ec27804..156d372 100644
--- a/src/util/digest.cpp
+++ b/src/util/digest.cpp
@@ -20,6 +20,7 @@
  */
 
 #include "digest.hpp"
+#include <sstream>
 
 namespace ndn {
 namespace util {