diff --git a/pkgs/os-specific/linux/kernel/htmldocs.nix b/pkgs/os-specific/linux/kernel/htmldocs.nix
index af43f3162783..5f5ce7c94e8c 100644
--- a/pkgs/os-specific/linux/kernel/htmldocs.nix
+++ b/pkgs/os-specific/linux/kernel/htmldocs.nix
@@ -23,7 +23,7 @@ stdenv.mkDerivation {
       tools/net/ynl/pyynl/ynl_gen_rst.py
   '';
 
-  FONTCONFIG_FILE = makeFontsConf {
+  env.FONTCONFIG_FILE = makeFontsConf {
     fontDirectories = [ ];
   };