diff --git a/pkgs/tools/typesetting/tex/texlive/combine.nix b/pkgs/tools/typesetting/tex/texlive/combine.nix
index ea292674819..d2608f89787 100644
--- a/pkgs/tools/typesetting/tex/texlive/combine.nix
+++ b/pkgs/tools/typesetting/tex/texlive/combine.nix
@@ -31,6 +31,12 @@ let
       ++ lib.optional (lib.any pkgNeedsRuby splitBin.wrong) ruby;
   };
 
+  # TODO: replace by buitin once it exists
+  fastUnique = comparator: list: with lib;
+    let un_adj = l: if length l < 2 then l
+      else optional (head l != elemAt l 1) (head l) ++ un_adj (tail l);
+    in un_adj (lib.sort comparator list);
+
   mkUniquePkgs = pkgs: fastUnique (a: b: a < b) # highlighting hack: >
     # here we deal with those dummy packages needed for hyphenation filtering
     (map (p: if lib.isDerivation p then p.outPath else "") pkgs);
diff --git a/pkgs/tools/typesetting/tex/texlive/default.nix b/pkgs/tools/typesetting/tex/texlive/default.nix
index 4904a60822a..05e078f8be8 100644
--- a/pkgs/tools/typesetting/tex/texlive/default.nix
+++ b/pkgs/tools/typesetting/tex/texlive/default.nix
@@ -24,7 +24,7 @@ let
 
   # function for creating a working environment from a set of TL packages
   combine = import ./combine.nix {
-    inherit bin combinePkgs buildEnv fastUnique lib makeWrapper writeText
+    inherit bin combinePkgs buildEnv lib makeWrapper writeText
       stdenv python ruby perl;
     ghostscript = ghostscriptX; # could be without X, probably, but we use X above
   };
@@ -171,12 +171,6 @@ let
   combinePkgs = pkgSet: lib.concatLists # uniqueness is handled in `combine`
     (lib.mapAttrsToList (_n: a: a.pkgs) pkgSet);
 
-  # TODO: replace by buitin once it exists
-  fastUnique = comparator: list: with lib;
-    let un_adj = l: if length l < 2 then l
-      else optional (head l != elemAt l 1) (head l) ++ un_adj (tail l);
-    in un_adj (lib.sort comparator list);
-
 in
   tl // {
     inherit bin combine;