diff --git a/finetune_csv/finetune_base_model.py b/finetune_csv/finetune_base_model.py
index d21c22db..915d81a8 100644
--- a/finetune_csv/finetune_base_model.py
+++ b/finetune_csv/finetune_base_model.py
@@ -121,8 +121,11 @@ def __getitem__(self, idx):
         
         x = window_data[self.feature_list].values.astype(np.float32)
         x_stamp = window_data[self.time_feature_list].values.astype(np.float32)
-        
-        x_mean, x_std = np.mean(x, axis=0), np.std(x, axis=0)
+
+        # Compute normalization stats only on the lookback portion to prevent
+        # future data leakage into the prediction window statistics.
+        past_x = x[:self.lookback_window]
+        x_mean, x_std = np.mean(past_x, axis=0), np.std(past_x, axis=0)
         x = (x - x_mean) / (x_std + 1e-5)
         x = np.clip(x, -self.clip, self.clip)