diff --git a/client/pool-buffer.c b/client/pool-buffer.c
index fa468c0d6..6555a3ae8 100644
--- a/client/pool-buffer.c
+++ b/client/pool-buffer.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <assert.h>
 #include <cairo/cairo.h>
 #include <fcntl.h>
diff --git a/sway/commands.c b/sway/commands.c
index d9c54adc4..f321a8743 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <ctype.h>
 #include <stdarg.h>
 #include <stdlib.h>
diff --git a/sway/commands/bar.c b/sway/commands/bar.c
index f6a70c175..9d62dc837 100644
--- a/sway/commands/bar.c
+++ b/sway/commands/bar.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <string.h>
 #include <strings.h>
 #include <wlr/util/log.h>
diff --git a/sway/commands/output/background.c b/sway/commands/output/background.c
index 748948120..900a5e753 100644
--- a/sway/commands/output/background.c
+++ b/sway/commands/output/background.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <libgen.h>
 #include <strings.h>
 #include <unistd.h>
diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index 60256336f..e7c1e36b8 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <ctype.h>
 #include <limits.h>
 #include <stdbool.h>
diff --git a/swaybar/ipc.c b/swaybar/ipc.c
index c2d05920f..972869c6f 100644
--- a/swaybar/ipc.c
+++ b/swaybar/ipc.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <limits.h>
 #include <string.h>
 #include <strings.h>