diff --git a/pkgs/development/libraries/cgui/default.nix b/pkgs/development/libraries/cgui/default.nix
index 39ed74d00750..d6c550a8da87 100644
--- a/pkgs/development/libraries/cgui/default.nix
+++ b/pkgs/development/libraries/cgui/default.nix
@@ -23,5 +23,6 @@ stdenv.mkDerivation rec {
     description = "A multiplatform basic GUI library";
     maintainers = [ maintainers.raskin ];
     platforms = platforms.linux;
+    license = licenses.free;
   };
 }