diff --git a/gateware/rtl/top.v b/gateware/rtl/top.v
index 4d0c8a3..c230bf8 100644
--- a/gateware/rtl/top.v
+++ b/gateware/rtl/top.v
@@ -326,7 +326,7 @@ module top (
 	// Unused
 	// ------
 
-	assign hp_p = clk_sys;
+	assign hp_p = 1'bz;
 	assign hp_n = 1'bz;
 
 endmodule // top