diff --git a/tools/Makefile b/tools/Makefile
index bac6aaf..097cc1d 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -172,10 +172,10 @@
 # Define __KERNEL_STRICT_NAMES to prevent typedef overlaps
 # Define _GNU_SOURCE to obtain the getline prototype from stdio.h
 #
-HOST_EXTRACFLAGS += -include $(SRCTREE)/include/libfdt_env.h \
+HOST_EXTRACFLAGS += -include $(srctree)/include/libfdt_env.h \
 		$(patsubst -I%,-idirafter%, $(UBOOTINCLUDE)) \
-		-I$(SRCTREE)/lib/libfdt \
-		-I$(SRCTREE)/tools \
+		-I$(srctree)/lib/libfdt \
+		-I$(srctree)/tools \
 		-DCONFIG_SYS_TEXT_BASE=$(CONFIG_SYS_TEXT_BASE) \
 		-DUSE_HOSTCC \
 		-D__KERNEL_STRICT_NAMES \