diff --git a/Dockerfile b/Dockerfile
index f2edc01..d9be28b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -48,7 +48,7 @@ EXPOSE 8080
 
 # launch and configure Unit
 RUN \
-	-f /var/www/html/index.php ] || { \
+	[ -f /var/www/html/index.php ] || { \
 	  touch /var/www/html/index.php /var/www/html/index.php.remove; \
 	} \
 	&& unitd --control unix:/var/run/control.unit.sock \