diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index 8c6ebb8..0b56b67 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -127,6 +127,7 @@
 			"GOMA_USE_LOCAL",
 
 			// RBE client
+			"FLAG_compare",
 			"FLAG_exec_root",
 			"FLAG_exec_strategy",
 			"FLAG_invocation_id",