diff --git a/usr/local/bin/systemd_check b/usr/local/bin/systemd_check
index cbad7b0..134aa1b 100755
--- a/usr/local/bin/systemd_check
+++ b/usr/local/bin/systemd_check
@@ -79,18 +79,21 @@ function checkService() {
 	if [ "$(id -u)" != "0" ]; then
 		local USER_COMMAND="systemctl --user is-active --quiet $SERVICE";
 		RESULT=$($USER_COMMAND);
+		if [ -z "$RESULT" ]; then
+			RESULT=0;
+		fi
 	else
 		local ROOT_COMMAND="systemctl is-active --quiet $SERVICE";
 		local USER_COMMAND="systemctl --user is-active --quiet $SERVICE";
 		local RESULT_ROOT_COMMAND=$($ROOT_COMMAND);
 		local RESULT_USER_COMMAND=$($USER_COMMAND);
 
-		if [ "$RESULT_ROOT_COMMAND" ] || [ "$RESULT_USER_COMMAND" ]; then
+		if [ -z "$RESULT_ROOT_COMMAND" ] || [ -z "$RESULT_USER_COMMAND" ]; then
 			RESULT=0;
 		fi
 	fi
 
-	if ! "$RESULT"; then
+	if [ "$RESULT" -gt 0 ]; then
 		local SUBJECT="[systemd $SYSTEMD_CHECK_HOSTNAME for $SYSTEMD_CHECK_USER] CRITICAL $SERVICE";
 		echo "-> $SUBJECT: $MESSAGE";