diff --git a/neuroglia/event.py b/neuroglia/event.py
index 95cb832..68dd113 100644
--- a/neuroglia/event.py
+++ b/neuroglia/event.py
@@ -84,6 +84,6 @@ def extractor(ev):
         tensor = xr.concat(tensor,dim=concat_dim)
 
         if self.fillna:
-            tensor.fillna(0.0)
+            tensor = tensor.fillna(0)
 
         return tensor