--- a/meson.build	2018-03-02 19:07:27.075804300 +0100
+++ b/meson.build	2018-03-02 19:17:55.025815868 +0100
@@ -481,7 +481,8 @@
 endforeach
 
 foreach ident : [
-        ['memfd_create',      '''#include <sys/memfd.h>'''],
+        ['memfd_create',      '''#define _GNU_SOURCE
+                                 #include <sys/mman.h>'''],
         ['gettid',            '''#include <sys/types.h>'''],
         ['pivot_root',        '''#include <stdlib.h>'''],     # no known header declares pivot_root
         ['name_to_handle_at', '''#define _GNU_SOURCE
@@ -494,7 +495,8 @@
         ['kcmp',              '''#include <linux/kcmp.h>'''],
         ['keyctl',            '''#include <sys/types.h>
                                  #include <keyutils.h>'''],
-        ['copy_file_range',   '''#include <sys/syscall.h>
+        ['copy_file_range',   '''#define _GNU_SOURCE
+                                 #include <sys/syscall.h>
                                  #include <unistd.h>'''],
         ['bpf',               '''#include <sys/syscall.h>
                                  #include <unistd.h>'''],
--- a/src/basic/fileio.c	2018-03-02 19:20:22.485818585 +0100
+++ b/src/basic/fileio.c	2018-03-02 19:20:40.799152256 +0100
@@ -24,6 +24,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>