diff --git a/core/build_id.mk b/core/build_id.mk
index 932e2144a..bac2f4809 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-export BUILD_ID=PI
+BUILD_ID=PI