diff --git a/src/seemps/state/mps.py b/src/seemps/state/mps.py
index 4c7454c..a4a4561 100644
--- a/src/seemps/state/mps.py
+++ b/src/seemps/state/mps.py
@@ -86,7 +86,7 @@ def bond_dimensions(self) -> list[int]:
 
     def max_bond_dimension(self) -> int:
         """Return the largest bond dimension."""
-        return max(a.shape[1] for a in self._data)
+        return max(a.shape[-1] for a in self._data)
 
     def to_vector(self) -> Vector:
         """Convert this MPS to a state vector."""