diff --git a/relay.c b/relay.c
index 5d240cf..b2a9838 100644
--- a/relay.c
+++ b/relay.c
@@ -40,7 +40,7 @@ static void send_sexp_syntax_error(IOHandle *h, char const *message) {
   INCREF(m);
 
   iohandle_clear_error(h);
-  ICHECK(sexp_write(h, m), "send_sexp_syntax_error sexp_write");
+  BCHECK(!sexp_write(h, m), "send_sexp_syntax_error sexp_write");
   DECREF(m, sexp_destructor);
   iohandle_flush(h); /* ignore result here, there's not much we can do with it */
 }