diff --git a/pkgs/build-support/build-fhs-userenv/env.nix b/pkgs/build-support/build-fhs-userenv/env.nix
index c776abe761d..04b4c10237a 100644
--- a/pkgs/build-support/build-fhs-userenv/env.nix
+++ b/pkgs/build-support/build-fhs-userenv/env.nix
@@ -39,12 +39,12 @@ let
   # builds.
   basePkgs = with pkgs;
     [ (if isMultiBuild then glibc_multi else glibc)
-      gcc.cc.lib bashInteractive coreutils less shadow su
+      (toString gcc.cc.lib) bashInteractive coreutils less shadow su
       gawk diffutils findutils gnused gnugrep
       gnutar gzip bzip2 xz glibcLocales
     ];
   baseMultiPkgs = with pkgsi686Linux;
-    [ gcc.cc.lib
+    [ (toString gcc.cc.lib)
     ];
 
   etcProfile = writeText "profile" ''