diff --git a/ucsb2.json b/ucsb2.json
index d24504c..630597d 100644
--- a/ucsb2.json
+++ b/ucsb2.json
@@ -5,6 +5,7 @@
     "hw_rev": "v2.0",
     "base": "standalone",
     "core_addr": "192.168.1.75",
+    "ext_ref_frequency": 125e6,
     "peripherals": [
         {
             "type": "dio",