diff --git a/pkgs/tools/text/ansifilter/default.nix b/pkgs/tools/text/ansifilter/default.nix
index 97b06b9a0c7e..79aa4e2debcd 100644
--- a/pkgs/tools/text/ansifilter/default.nix
+++ b/pkgs/tools/text/ansifilter/default.nix
@@ -14,6 +14,8 @@ stdenv.mkDerivation rec {
 
   postPatch = ''
     substituteInPlace src/makefile --replace "CC=g++" "CC=c++"
+    # avoid timestamp non-determinism with '-n'
+    substituteInPlace makefile --replace 'gzip -9f' 'gzip -9nf'
   '';
 
   makeFlags = [