diff --git a/require-ess/tools/driver.makefile b/require-ess/tools/driver.makefile
index 270c88b1cfe1aabb2cb4784d59794e67c74b126b..e812edd77dcf1fe2874b8d1be6e76295c3a30712 100644
--- a/require-ess/tools/driver.makefile
+++ b/require-ess/tools/driver.makefile
@@ -145,7 +145,7 @@ endef
 #   $(call FETCH_BUILD_NUMBER,$(E3_SITEMODS_PATH),module)
 #
 define FETCH_BUILD_NUMBER
-$(shell $(E3_REQUIRE_TOOLS)/build_number.sh $(1) $(2) $($(2)_VERSION))
+$(shell $(MAKEHOME)/build_number.sh $(1) $(2) $($(2)_VERSION))
 endef
 
 ifndef EPICSVERSION