diff --git a/CHANGELOG.md b/CHANGELOG.md
index 868d719b5..89b6eb443 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,8 @@ we hit release version 1.0.0.
       import sisl
       sisl.geom.graphene
 
+- added Nambu spin configuration, this is still experimental
+
 ### Fixed
 - `projection` arguments of several functions has been streamlined
 
diff --git a/src/sisl/physics/spin.py b/src/sisl/physics/spin.py
index 338fe15d2..c77a241f8 100644
--- a/src/sisl/physics/spin.py
+++ b/src/sisl/physics/spin.py
@@ -8,6 +8,7 @@
 import numpy as np
 
 from sisl._internal import set_module
+from sisl.messages import warn
 
 __all__ = ["Spin"]
 
@@ -100,6 +101,11 @@ def __init__(self, kind: Union[str, int] = "unpolarized"):
                 f"{self.__class__.__name__} initialization went wrong because of wrong "
                 "kind specification. Could not determine the kind of spin!"
             )
+        if kind == Spin.NAMBU:
+            warn(
+                "Using untested Nambu spin-configuration, please be aware "
+                "that this is largely untested code!"
+            )
 
         # Now assert the checks
         self._kind = kind