diff --git a/data/spot.py b/data/spot.py
index a41ccfa..fa6da6a 100644
--- a/data/spot.py
+++ b/data/spot.py
@@ -224,8 +224,8 @@ class Spot:
         if self.mode and not self.mode_type:
             self.mode_type = lookup_helper.infer_mode_type_from_mode(self.mode)
 
-        # If we have a latitude at this point, it can only have been provided by the spot itself
-        if self.dx_latitude:
+        # If we have a latitude or grid at this point, it can only have been provided by the spot itself
+        if self.dx_latitude or self.dx_grid:
             self.dx_location_source = "SPOT"
 
         # Set the top-level "SIG" if it is missing but we have at least one SIG ref.