diff --git a/pkgs/tools/filesystems/reiserfsprogs/default.nix b/pkgs/tools/filesystems/reiserfsprogs/default.nix
index a89ea0657500..10962f10a8f5 100644
--- a/pkgs/tools/filesystems/reiserfsprogs/default.nix
+++ b/pkgs/tools/filesystems/reiserfsprogs/default.nix
@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ autoreconfHook ];
   buildInputs = [ libuuid ];
 
-  NIX_CFLAGS_COMPILE = "-std=gnu90";
+  NIX_CFLAGS_COMPILE = [ "-std=gnu90" "-D_GNU_SOURCE" ];
 
   meta = {
     inherit version;