diff --git a/ndn-cpp/c/encoding/binary-xml-key.c b/ndn-cpp/c/encoding/binary-xml-key.c
index 769ea16..4be24af 100644
--- a/ndn-cpp/c/encoding/binary-xml-key.c
+++ b/ndn-cpp/c/encoding/binary-xml-key.c
@@ -61,7 +61,7 @@
 
 ndn_Error ndn_encodeBinaryXmlKeyLocator(struct ndn_KeyLocator *keyLocator, struct ndn_BinaryXmlEncoder *encoder)
 {
-  if (keyLocator->type < 0)
+  if ((int)keyLocator->type < 0)
     return NDN_ERROR_success;
 
   ndn_Error error;