diff --git a/ndn-cpp/publisher-public-key-digest.hpp b/ndn-cpp/publisher-public-key-digest.hpp
index 6abe8bd..1c04b3a 100644
--- a/ndn-cpp/publisher-public-key-digest.hpp
+++ b/ndn-cpp/publisher-public-key-digest.hpp
@@ -58,7 +58,7 @@
   }
   
   void 
-  setPublisherPublicKeyDigest(const uint8_t *publisherPublicKeyDigest, unsigned int publisherPublicKeyDigestLength) 
+  setPublisherPublicKeyDigest(const uint8_t *publisherPublicKeyDigest, size_t publisherPublicKeyDigestLength) 
   { 
     publisherPublicKeyDigest_ = Blob(publisherPublicKeyDigest, publisherPublicKeyDigestLength); 
   }