diff --git a/explaining_framework/metric/sparsity.py b/explaining_framework/metric/sparsity.py
index b3f7a61..067f0c6 100644
--- a/explaining_framework/metric/sparsity.py
+++ b/explaining_framework/metric/sparsity.py
@@ -1,4 +1,5 @@
 import torch
+from torch_geometric.explain.explanation import Explanation
 
 from explaining_framework.metric.base import Metric