Do not run colliding tests at same time
diff --git a/meson.build b/meson.build
index 7bacdfc..975d56c 100644
--- a/meson.build
+++ b/meson.build
@@ -108,6 +108,7 @@
 test(
   'jsonchecker_jsontestrunner',
   python,
+  is_parallel : false,
   args : [
     '-B',
     join_paths(meson.current_source_dir(), 'test/runjsontests.py'),