diff --git a/torch_scatter/composite/logsumexp.py b/torch_scatter/composite/logsumexp.py
index 69dc90dd..1d5ff9b6 100644
--- a/torch_scatter/composite/logsumexp.py
+++ b/torch_scatter/composite/logsumexp.py
@@ -38,7 +38,7 @@ def scatter_logsumexp(
     recentered_score = src - max_per_src_element
     recentered_score.masked_fill_(torch.isnan(recentered_score), float('-inf'))
 
-    orig_out = None
+    orig_out: Optional[torch.Tensor] = None
     if out is not None:
         orig_out = out.clone()
         out = out.sub_(max_value_per_index).exp_()