diff --git a/pkgs/tools/misc/ttyrec/default.nix b/pkgs/tools/misc/ttyrec/default.nix
index 63b91adb4936..a836a2a0d0e9 100644
--- a/pkgs/tools/misc/ttyrec/default.nix
+++ b/pkgs/tools/misc/ttyrec/default.nix
@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
 
   patches = [ ./clang-fixes.patch ];
 
-  makeFlags = []
+  makeFlags = [ "CFLAGS=-DSVR4" ]
     ++ stdenv.lib.optional stdenv.cc.isClang "CC=clang";
 
   installPhase = ''