diff --git a/ndn-cpp/c/encoding/binary-xml-data.c b/ndn-cpp/c/encoding/binary-xml-data.c
index 8da14b2..ad9ffbf 100644
--- a/ndn-cpp/c/encoding/binary-xml-data.c
+++ b/ndn-cpp/c/encoding/binary-xml-data.c
@@ -59,7 +59,7 @@
 static ndn_Error encodeSignedInfo(struct ndn_SignedInfo *signedInfo, struct ndn_BinaryXmlEncoder *encoder)
 {
   if (signedInfo->type < 0)
-    return;
+    return 0;
 
   ndn_Error error;
   if (error = ndn_BinaryXmlEncoder_writeElementStartDTag(encoder, ndn_BinaryXml_DTag_SignedInfo))