diff --git a/include/meson.build b/include/meson.build
index 358e04976..2f8882803 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -4,7 +4,10 @@ dri_dep = dependency('dri', required: build_dri2 or build_dri3)
 conf_data = configuration_data()
 conf_data.set('_DIX_CONFIG_H_', '1')
 
+
+
 conf_data.set('MONOTONIC_CLOCK', cc.compiles('''
+    #define _POSIX_C_SOURCE 200112L
     #include <time.h>
     #include <unistd.h>
     #ifndef CLOCK_MONOTONIC