diff --git a/ui/build/rbe.go b/ui/build/rbe.go
index 3b9d301..19a54df 100644
--- a/ui/build/rbe.go
+++ b/ui/build/rbe.go
@@ -55,13 +55,14 @@
 
 func getRBEVars(ctx Context, config Config) map[string]string {
 	vars := map[string]string{
-		"RBE_log_dir":       config.rbeProxyLogsDir(),
-		"RBE_re_proxy":      config.rbeReproxy(),
-		"RBE_exec_root":     config.rbeExecRoot(),
-		"RBE_output_dir":    config.rbeProxyLogsDir(),
-		"RBE_proxy_log_dir": config.rbeProxyLogsDir(),
-		"RBE_cache_dir":     config.rbeCacheDir(),
-		"RBE_platform":      "container-image=" + remoteexec.DefaultImage,
+		"RBE_log_dir":          config.rbeProxyLogsDir(),
+		"RBE_re_proxy":         config.rbeReproxy(),
+		"RBE_exec_root":        config.rbeExecRoot(),
+		"RBE_output_dir":       config.rbeProxyLogsDir(),
+		"RBE_proxy_log_dir":    config.rbeProxyLogsDir(),
+		"RBE_cache_dir":        config.rbeCacheDir(),
+		"RBE_download_tmp_dir": config.rbeDownloadTmpDir(),
+		"RBE_platform":         "container-image=" + remoteexec.DefaultImage,
 	}
 	if config.StartRBE() {
 		name, err := config.rbeSockAddr(absPath(ctx, config.TempDir()))