diff --git a/npc/core/src/test/scala/Keyboard.scala b/npc/core/src/test/scala/Keyboard.scala
index 24723cc..92ecadb 100644
--- a/npc/core/src/test/scala/Keyboard.scala
+++ b/npc/core/src/test/scala/Keyboard.scala
@@ -60,13 +60,3 @@ class KeyboardControllerSpec extends AnyFreeSpec with ChiselScalatestTester {
     }
   }
 }
-
-class SegSpec extends AnyFreeSpec with ChiselScalatestTester {
-  "try out vec" in {
-    test(new SegGenerator(8)) {c =>
-      c.io.keycode.bits.poke(0xAC)
-      c.clock.step(1)
-      println(s"out: ${c.io.segs(0).peek().litValue}")
-    }
-  }
-}
diff --git a/npc/flake.nix b/npc/flake.nix
index b2fd2fa..32aa36a 100644
--- a/npc/flake.nix
+++ b/npc/flake.nix
@@ -37,6 +37,7 @@
             sbt
             nur.xin.nvboard
             self.packages.${system}.circt
+            yosys
           ];
           buildInputs = [
             verilator