diff --git a/qiskit/quantum_info/operators/symplectic/sparse_pauli_op.py b/qiskit/quantum_info/operators/symplectic/sparse_pauli_op.py
index 36361f8e4e2b..5fc9dafe7845 100644
--- a/qiskit/quantum_info/operators/symplectic/sparse_pauli_op.py
+++ b/qiskit/quantum_info/operators/symplectic/sparse_pauli_op.py
@@ -240,6 +240,7 @@ def paulis(self, value):
         if len(value) != len(self.paulis):
             raise ValueError(f"Length must match; expected: {len(self.paulis)} got: {len(value)}")
         self._pauli_list = value
+        super().__init__(num_qubits=self._pauli_list.num_qubits)
 
     @property
     def coeffs(self):