diff --git a/src/datasets/features/features.py b/src/datasets/features/features.py
index dd41be8bd95..0b2d0e27820 100644
--- a/src/datasets/features/features.py
+++ b/src/datasets/features/features.py
@@ -1095,7 +1095,7 @@ def cast_storage(self, storage: Union[pa.StringArray, pa.IntegerArray]) -> pa.In
         """
         if isinstance(storage, pa.IntegerArray) and len(storage) > 0:
             min_max = pc.min_max(storage).as_py()
-            if min_max["max"] >= self.num_classes:
+            if min_max["max"] is not None and min_max["max"] >= self.num_classes:
                 raise ValueError(
                     f"Class label {min_max['max']} greater than configured num_classes {self.num_classes}"
                 )