diff --git a/odc/geo/_xr_interop.py b/odc/geo/_xr_interop.py
index 2ca3cb0f..4be83c07 100644
--- a/odc/geo/_xr_interop.py
+++ b/odc/geo/_xr_interop.py
@@ -50,7 +50,7 @@
 )
 from .overlap import compute_output_geobox
 from .roi import roi_is_empty
-from .types import Nodata, Resolution, SomeNodata, SomeResolution, SomeShape, xy_
+from .types import Nodata, Resolution, SomeNodata, SomeResolution, SomeShape, Unset, xy_
 
 # pylint: disable=import-outside-toplevel
 # pylint: disable=too-many-lines
@@ -80,6 +80,8 @@
     ("lat", "lon"),
 ]
 
+_NoValue = Unset()
+
 
 @dataclass
 class GeoState:
@@ -1024,11 +1026,11 @@ def nodata(self) -> Nodata:
         encoding = self._xx.encoding
 
         for k in ["nodata", "_FillValue"]:
-            nodata = attrs.get(k, ())
-            if nodata == ():
-                nodata = encoding.get(k, ())
+            nodata = attrs.get(k, _NoValue)
+            if nodata is _NoValue:
+                nodata = encoding.get(k, _NoValue)
 
-            if nodata == ():
+            if nodata is _NoValue:
                 continue
 
             if nodata is None: