diff --git a/pkgs/development/libraries/ptlib/default.nix b/pkgs/development/libraries/ptlib/default.nix
index ae60a6f69d6..d425de243f5 100644
--- a/pkgs/development/libraries/ptlib/default.nix
+++ b/pkgs/development/libraries/ptlib/default.nix
@@ -38,6 +38,7 @@ stdenv.mkDerivation rec {
     description = "Portable Tools from OPAL VoIP";
     maintainers = [ maintainers.raskin ];
     platforms = platforms.linux;
+    license = with licenses; [ beerware bsdOriginal mpl10 ];
   };
 
   passthru = {