diff --git a/ui/build/soong.go b/ui/build/soong.go
index 3388417..afbc073 100644
--- a/ui/build/soong.go
+++ b/ui/build/soong.go
@@ -119,6 +119,7 @@
 			"-j", strconv.Itoa(config.Parallel()),
 			"--frontend_file", fifo,
 			"-f", filepath.Join(config.SoongOutDir(), file))
+		cmd.Environment.Set("SOONG_SANDBOX_SOONG_BUILD", "true")
 		cmd.Sandbox = soongSandbox
 		cmd.RunAndStreamOrFatal()
 	}