diff --git a/include/chibi/features.h b/include/chibi/features.h
index f7394bda..9308d4c6 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -560,7 +560,7 @@
 #endif
 
 #ifndef SEXP_USE_BIDIRECTIONAL_PORTS
-#define SEXP_USE_BIDIRECTIONAL_PORTS ! SEXP_USE_NO_FEATURES
+#define SEXP_USE_BIDIRECTIONAL_PORTS 0
 #endif
 
 #ifndef SEXP_PORT_BUFFER_SIZE