diff --git a/include/ndn-cpp/data.hpp b/include/ndn-cpp/data.hpp
index 3f0d00b..d25253f 100644
--- a/include/ndn-cpp/data.hpp
+++ b/include/ndn-cpp/data.hpp
@@ -273,6 +273,9 @@
   wire_ = Block();
 }
 
+std::ostream&
+operator << (std::ostream &os, const Data &data);
+
 } // namespace ndn
 
 #endif
diff --git a/include/ndn-cpp/meta-info.hpp b/include/ndn-cpp/meta-info.hpp
index 27e97e8..3a33dc4 100644
--- a/include/ndn-cpp/meta-info.hpp
+++ b/include/ndn-cpp/meta-info.hpp
@@ -111,6 +111,19 @@
     }
 }
 
+inline std::ostream&
+operator << (std::ostream &os, const MetaInfo &info)
+{
+  // ContentType
+  os << "ContentType: " << info.getType();
+
+  // FreshnessPeriod
+  if (info.getFreshnessPeriod() >= 0) {
+    os << ", FreshnessPeriod: " << info.getFreshnessPeriod();
+  }
+  return os;
+}
+
 } // namespace ndn
 
 #endif // NDN_META_INFO_HPP