diff --git a/pkgs/os-specific/linux/tmon/default.nix b/pkgs/os-specific/linux/tmon/default.nix
index 3b306b193f80..1a299ad50669 100644
--- a/pkgs/os-specific/linux/tmon/default.nix
+++ b/pkgs/os-specific/linux/tmon/default.nix
@@ -23,7 +23,8 @@ stdenv.mkDerivation {
     "INSTALL_ROOT=\"$(out)\""
     "BINDIR=bin"
   ];
-  NIX_CFLAGS_LINK = "-lgcc_s";
+
+  env.NIX_CFLAGS_LINK = "-lgcc_s";
 
   enableParallelBuilding = true;