diff --git a/Makefile b/Makefile
index 29597c8..b0a99146 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@
 
 additional-dirs :=
 
+VBOOT_SOURCE ?= $(abspath 3rdparty/vboot)
 VBOOT_HOST_BUILD ?= $(abspath $(objutil)/vboot_lib)
 
 COREBOOT_EXPORTS := COREBOOT_EXPORTS
diff --git a/Makefile.inc b/Makefile.inc
index e382518..2f810d5 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -460,7 +460,6 @@
 endif
 
 CPPFLAGS_common := -Isrc -Isrc/include -Isrc/commonlib/include -Isrc/commonlib/bsd/include -I$(obj)
-VBOOT_SOURCE ?= 3rdparty/vboot
 CPPFLAGS_common += -I$(VBOOT_SOURCE)/firmware/include
 CPPFLAGS_common += -include $(src)/include/kconfig.h
 CPPFLAGS_common += -include $(src)/include/rules.h
diff --git a/tests/Makefile.common b/tests/Makefile.common
index e51d253..9cc79d7 100644
--- a/tests/Makefile.common
+++ b/tests/Makefile.common
@@ -36,7 +36,7 @@
 
 TEST_INCLUDES += -I$(src) -I$(src)/include -I$(src)/commonlib/include \
 	-I$(src)/commonlib/bsd/include -I$(src)/arch/x86/include \
-	-I$(top)/3rdparty/vboot/firmware/include
+	-I$(VBOOT_SOURCE)/firmware/include
 
 # Path for Kconfig autoheader
 TEST_INCLUDES += -I$(dir $(TEST_KCONFIG_AUTOHEADER))