diff --git a/configure.ac b/configure.ac
index 8201a1f..3c6b387 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,6 +15,8 @@ AC_CONFIG_AUX_DIR([build])
 AC_CONFIG_SRCDIR([config.h.in])
 AC_CONFIG_HEADERS([config.h])
 
+AC_GNU_SOURCE
+
 AC_SUBST([WAYLAND_EXTERNAL_MAJOR_VERSION], [wayland_eglstream_major_version])
 AC_SUBST([WAYLAND_EXTERNAL_MINOR_VERSION], [wayland_eglstream_minor_version])
 AC_SUBST([WAYLAND_EXTERNAL_MICRO_VERSION], [wayland_eglstream_micro_version])
diff --git a/src/meson.build b/src/meson.build
index 5a5e4e0..af92ee8 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -8,6 +8,7 @@ add_project_arguments('-Wall', language : 'c')
 add_project_arguments('-Werror', language : 'c')
 add_project_arguments('-fvisibility=hidden', language : 'c')
 add_project_arguments('-DWL_HIDE_DEPRECATED', language : 'c')
+add_project_arguments('-D_GNU_SOURCE', language : 'c')
 add_project_link_arguments('-Wl,-Bsymbolic', language : 'c')
 
 if cc.has_argument('-Wpedantic')