diff --git a/pkgs/applications/networking/mailreaders/thunderbird/default.nix b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
index e9ae6696def..3b0be4dad19 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
@@ -336,5 +336,6 @@ stdenv.mkDerivation rec {
       pierron
     ];
     platforms = platforms.linux;
+    license = licenses.mpl20;
   };
 }