diff --git a/ptbin.json b/ptbin.json
index 75b62f5..17da738 100644
--- a/ptbin.json
+++ b/ptbin.json
@@ -30,12 +30,14 @@
         {
             "type": "urukul",
             "ports": [5, 4],
+            "ref_frequency": 100e6,
             "clk_sel": 0
         },
         {
             "type": "urukul",
             "ports": [6],
             "dds": "ad9912",
+            "ref_frequency": 100e6,
             "clk_sel": 0
         },
         {