diff --git a/board/tcm-bf537/config.mk b/board/tcm-bf537/config.mk
index 973d357..97eaafe 100644
--- a/board/tcm-bf537/config.mk
+++ b/board/tcm-bf537/config.mk
@@ -7,9 +7,10 @@
 # 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
 
 # Set some default LDR flags based on boot mode.
 LDR_FLAGS-BFIN_BOOT_PARA := --bits 16 --dma 8