diff --git a/avalanche/models/pnn.py b/avalanche/models/pnn.py
index 693ed9ebc..792324923 100644
--- a/avalanche/models/pnn.py
+++ b/avalanche/models/pnn.py
@@ -20,6 +20,7 @@ def __init__(self, in_features, out_features_per_column, num_prev_modules):
         :param num_prev_modules: number of previous modules
         """
         super().__init__()
+        self.num_prev_modules = num_prev_modules
         # Eq. 1 - lateral connections
         # one layer for each previous column. Empty for the first task.
         self.lat_layers = nn.ModuleList([])