diff --git a/lib/licenses.nix b/lib/licenses.nix
index 850de29e7d1..d47deccfec3 100644
--- a/lib/licenses.nix
+++ b/lib/licenses.nix
@@ -703,6 +703,12 @@ lib.mapAttrs (n: v: v // { shortName = n; }) {
     free = false;
   };
 
+  stk = {
+    shortName = "stk";
+    fullName = "Synthesis Tool Kit 4.3";
+    url = https://github.com/thestk/stk/blob/master/LICENSE;
+  };
+
   tcltk = spdx {
     spdxId = "TCL";
     fullName = "TCL/TK License";