diff --git a/meson.build b/meson.build
index 25eb841942a1..38cb09019bc8 100644
--- a/meson.build
+++ b/meson.build
@@ -51,8 +51,7 @@ if m_dep.found()
   add_project_link_arguments('-lm', language : 'c')
 endif
 if host_machine.system() == 'os400'
-  add_global_arguments('-pthread', language : 'cpp')
-  add_global_arguments('-D__STDC_FORMAT_MACROS', language : 'cpp')
+  add_project_arguments('-D__STDC_FORMAT_MACROS', language : 'cpp')
   add_project_link_arguments('-Wl,-bnotextro', language : 'c')
   add_project_link_arguments('-Wl,-bnotextro', language : 'cpp')
   add_project_link_arguments('-Wl,-bnotextro', language : 'fortran')