diff --git a/cusp/system/cuda/detail/multiply/dia_spmv.h b/cusp/system/cuda/detail/multiply/dia_spmv.h
index c7523c02..bf381825 100644
--- a/cusp/system/cuda/detail/multiply/dia_spmv.h
+++ b/cusp/system/cuda/detail/multiply/dia_spmv.h
@@ -92,7 +92,7 @@ spmv_dia_kernel(const int num_rows,
         // process chunk
         for(IndexType row = thread_id; row < num_rows; row += grid_size)
         {
-            ValueType sum = (base == 0) ? initialize(y[row]) : ValueType(0);
+            ValueType sum = (base == 0) ? initialize(y[row]) : y[row];
 
             // index into values array
             IndexType idx = row + pitch * base;