diff --git a/litex_boards/platforms/crosslink_nx_evn.py b/litex_boards/platforms/crosslink_nx_evn.py
index d918c8bac5eb2af4e818dbab3632672741393ae1..fea222ed74620eb0250ec6f0200f8c4670626e9e 100644
--- a/litex_boards/platforms/crosslink_nx_evn.py
+++ b/litex_boards/platforms/crosslink_nx_evn.py
@@ -246,6 +246,9 @@ serial_pmods = [
 # Platform -----------------------------------------------------------------------------------------
 
 class Platform(LatticePlatform):
+    default_clk_name   = "clk12"
+    default_clk_period = 1e9/12e6
+
     def __init__(self, device="LIFCL", **kwargs):
         assert device in ["LIFCL"]
         LatticePlatform.__init__(self, device + "-40-9BG400C", _io, _connectors, toolchain="radiant", **kwargs)
diff --git a/litex_boards/platforms/crosslink_nx_vip.py b/litex_boards/platforms/crosslink_nx_vip.py
index b492511a3c5da3cf9f4fcca6d5dc2329f845bc28..326b9122a94f243e082f21fe4b4f70ed2c584fef 100644
--- a/litex_boards/platforms/crosslink_nx_vip.py
+++ b/litex_boards/platforms/crosslink_nx_vip.py
@@ -199,6 +199,9 @@ _connectors = [
 # Platform -----------------------------------------------------------------------------------------
 
 class Platform(LatticePlatform):
+    default_clk_name   = "clk12"
+    default_clk_period = 1e9/12e6
+
     def __init__(self, device="LIFCL", **kwargs):
         assert device in ["LIFCL"]
         LatticePlatform.__init__(self, device + "-40-9BG400C", _io, _connectors, toolchain="radiant", **kwargs)