diff --git a/tests/unit/check_readwrite.c b/tests/unit/check_readwrite.c
index c605d4d..3cb2ba3 100644
--- a/tests/unit/check_readwrite.c
+++ b/tests/unit/check_readwrite.c
@@ -57,7 +57,7 @@ void * responder( void *respond_uncast )
 			fd_write_reply( sock_fd, wrong_handle, 0 );
 		}
 		else {
-			fd_write_reply( sock_fd, resp->received.handle.w, 0 );
+			fd_write_reply( sock_fd, (char *) resp->received.handle.w, 0 );
 		}
 		write( sock_fd, "12345678", 8 );
 	}