diff --git a/pkgs/servers/mail/postfix/pfixtools.nix b/pkgs/servers/mail/postfix/pfixtools.nix
index 3e7ef9f23db5..b17beeb095f2 100644
--- a/pkgs/servers/mail/postfix/pfixtools.nix
+++ b/pkgs/servers/mail/postfix/pfixtools.nix
@@ -38,6 +38,8 @@ stdenv.mkDerivation {
                       --replace /bin/bash ${bash}/bin/bash;
   '';
 
+  NIX_CFLAGS_COMPILE = "-Wno-error=unused-result";
+
   makeFlags = "DESTDIR=$(out) prefix=";
 
   meta = {