diff --git a/meson.build b/meson.build
index 61fcff42..57b024c8 100644
--- a/meson.build
+++ b/meson.build
@@ -104,7 +104,7 @@ if scdoc.found()
 	endforeach
 endif
 
-add_project_arguments('-DSYSCONFDIR="/@0@"'.format(sysconfdir), language : 'c')
+add_project_arguments('-DSYSCONFDIR="/@0@/@1@"'.format(prefix, sysconfdir), language : 'c')
 
 version = get_option('sway_version')
 if version != ''