diff --git a/pkgs/tools/typesetting/tex/lkproof/default.nix b/pkgs/tools/typesetting/tex/lkproof/default.nix
index 844eadc4440..db0ec6d9bea 100644
--- a/pkgs/tools/typesetting/tex/lkproof/default.nix
+++ b/pkgs/tools/typesetting/tex/lkproof/default.nix
@@ -2,12 +2,12 @@
 
 stdenv.mkDerivation {
   name = "lkproof-3.1";
-  
+
   src = fetchurl {
     url = http://mirror.ctan.org/macros/latex/contrib/lkproof.zip;
     sha256 = "1qjkjhpc4rm62qxn18r83zdlwnj1wvnkcpdiqlv7w4bakh0gvjly";
   };
-  
+
   buildInputs = [ unzip ];
 
   installPhase = "
@@ -15,7 +15,8 @@ stdenv.mkDerivation {
     cp -prd *.sty $out/share/texmf-nix/tex/generic/lkproof
   ";
 
-  meta = {
-    platforms = stdenv.lib.platforms.unix;
+  meta = with stdenv.lib; {
+    platforms = platforms.unix;
+    license = licenses.gpl1Plus;
   };
 }