diff --git a/ndn-cpp/c/encoding/BinaryXMLPublisherPublicKeyDigest.c b/ndn-cpp/c/encoding/BinaryXMLPublisherPublicKeyDigest.c
index 8a1fe63..493ab8c 100644
--- a/ndn-cpp/c/encoding/BinaryXMLPublisherPublicKeyDigest.c
+++ b/ndn-cpp/c/encoding/BinaryXMLPublisherPublicKeyDigest.c
@@ -11,7 +11,7 @@
   (struct ndn_PublisherPublicKeyDigest *publisherPublicKeyDigest, struct ndn_BinaryXmlEncoder *encoder)
 {  
   if (!publisherPublicKeyDigest->publisherPublicKeyDigest || publisherPublicKeyDigest->publisherPublicKeyDigestLength == 0)
-    return;
+    return 0;
   
   ndn_Error error;
   if (error = ndn_BinaryXmlEncoder_writeBlobDTagElement