diff --git a/ndn-cpp/common.hpp b/ndn-cpp/common.hpp
index 0ed219c..70b36ed 100644
--- a/ndn-cpp/common.hpp
+++ b/ndn-cpp/common.hpp
@@ -58,7 +58,7 @@
  * @return Hex string.
  */
 std::string 
-toHex(const std::vector<unsigned char>& array);
+toHex(const std::vector<uint8_t>& array);
 
 }