diff --git a/ndn-cpp/c/encoding/BinaryXMLInterest.c b/ndn-cpp/c/encoding/BinaryXMLInterest.c
index b9de3d6..270e13b 100644
--- a/ndn-cpp/c/encoding/BinaryXMLInterest.c
+++ b/ndn-cpp/c/encoding/BinaryXMLInterest.c
@@ -12,7 +12,7 @@
 static ndn_Error encodeExclude(struct ndn_Exclude *exclude, struct ndn_BinaryXMLEncoder *encoder)
 {
   if (exclude->nEntries == 0)
-    return;
+    return 0;
   
   ndn_Error error;
   if (error = ndn_BinaryXMLEncoder_writeElementStartDTag(encoder, ndn_BinaryXML_DTag_Exclude))