diff --git a/loopy/expression.py b/loopy/expression.py
index 64172b88a6cc2dda17b60a6427cfcf9bf430600f..9d48a8f0073f3430f645087f7ba330b0112c6005 100644
--- a/loopy/expression.py
+++ b/loopy/expression.py
@@ -122,6 +122,8 @@ class VectorizabilityChecker(Mapper[bool, []]):
 
         index = expr.index_tuple
 
+        index = tuple(simplify_using_aff(self.kernel, idx_i) for idx_i in index)
+
         from pymbolic.primitives import Variable
 
         from loopy.kernel.array import VectorArrayDimTag