diff --git a/miplearn/solvers/learning.py b/miplearn/solvers/learning.py
index cce10f0..dbf5a4b 100644
--- a/miplearn/solvers/learning.py
+++ b/miplearn/solvers/learning.py
@@ -155,7 +155,7 @@ class LearningSolver:
 
         # Extract features
         # -------------------------------------------------------
-        if instance.features is None:
+        if instance.features.instance is None:
             logger.info("Extracting features...")
             FeaturesExtractor(self.internal_solver).extract(instance)