diff --git a/themes/binaryanomaly/binaryanomaly.theme.bash b/themes/binaryanomaly/binaryanomaly.theme.bash
index 9b572d7e90..3501e8d469 100644
--- a/themes/binaryanomaly/binaryanomaly.theme.bash
+++ b/themes/binaryanomaly/binaryanomaly.theme.bash
@@ -3,7 +3,7 @@
 
 # Detect whether a reboot is required
 function show_reboot_required() {
-	if [[ -n "${_bf_prompt_reboot_info}" ]]; then
+	if [[ -n "${_bf_prompt_reboot_info:-}" ]]; then
 		if [[ -f /var/run/reboot-required ]]; then
 			printf '%s' "Reboot required!"
 		fi