diff --git a/test/test-helper.el b/test/test-helper.el
index b6ccbaa..89c091c 100644
--- a/test/test-helper.el
+++ b/test/test-helper.el
@@ -55,6 +55,7 @@ Finally, the indented text in the buffer will be compared with AFTER."
     ;; for some reason, plantuml-mode disregards the setq-local
     (setq plantuml-jar-path plantuml-test-jar-path)
     (setq plantuml-default-exec-mode 'jar)
+    (setq plantuml-exec-mode 'jar)
     (plantuml-init-once)
 
     (insert before)