diff --git a/board/bct-brettl2/config.mk b/board/bct-brettl2/config.mk
index f1ef9bf..0d3df2d 100644
--- a/board/bct-brettl2/config.mk
+++ b/board/bct-brettl2/config.mk
@@ -7,6 +7,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-CFLAGS_lib += -O2
-CFLAGS_lib/lzma += -O2
-CFLAGS_lib/zlib += -O2
+# FIX ME
+ifneq ($(filter lib lib/lzma lib/zlib, $(obj)),)
+ccflags-y := -O2
+endif