diff --git a/src/httpbf/src/httpbf.c b/src/httpbf/src/httpbf.c
index deed15b9e3..a7ef583248 100644
--- a/src/httpbf/src/httpbf.c
+++ b/src/httpbf/src/httpbf.c
@@ -231,7 +231,7 @@ static char* get_transfer_url( hbf_transfer_t *transfer, int indx ) {
         return NULL;
       }
 
-      if( sprintf(res, "%s-chunking-%d-%d-%d", transfer->url, transfer->transfer_id,
+      if( sprintf(res, "%s-chunking-%u-%u-%u", transfer->url, transfer->transfer_id,
                    transfer->block_cnt, indx ) < 0 ) {
         return NULL;
       }