diff --git a/update-makefiles.sh b/update-makefiles.sh
index 88cc97b..b7e4235 100755
--- a/update-makefiles.sh
+++ b/update-makefiles.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-source system/tools/hidl/update-makefiles-helper.sh
+source $ANDROID_BUILD_TOP/system/tools/hidl/update-makefiles-helper.sh
 
 do_makefiles_update \
   "android.hardware:hardware/interfaces" \