diff --git a/fem/PyNucleus_fem/distributed_operators_{SCALAR}.pxi b/fem/PyNucleus_fem/distributed_operators_{SCALAR}.pxi
index 04be2c94..05095644 100644
--- a/fem/PyNucleus_fem/distributed_operators_{SCALAR}.pxi
+++ b/fem/PyNucleus_fem/distributed_operators_{SCALAR}.pxi
@@ -162,6 +162,7 @@ cdef class {SCALAR_label}CSR_DistributedLinearOperator({SCALAR_label}Distributed
         else:
             w = resAcc
 
+        w[:] = 0.
         for k in range(self.overlap_indices.shape[0]):
             i = self.overlap_indices[k]
             temp = rhs[i]