diff --git a/pyFTS/models/ifts.py b/pyFTS/models/ifts.py
index 4987c73..0826159 100644
--- a/pyFTS/models/ifts.py
+++ b/pyFTS/models/ifts.py
@@ -13,7 +13,7 @@ from pyFTS.common import FuzzySet, FLR, fts, tree
 from pyFTS.models import hofts
 
 
-class IntervalFTS(hofts.HighOrderFTS):
+class IntervalFTS(hofts.WeightedHighOrderFTS):
     """
     High Order Interval Fuzzy Time Series
     """