diff --git a/common/unified/matrix/dense_kernels.template.cpp b/common/unified/matrix/dense_kernels.template.cpp
index 05966ede9d3..9258fdf8a46 100644
--- a/common/unified/matrix/dense_kernels.template.cpp
+++ b/common/unified/matrix/dense_kernels.template.cpp
@@ -263,7 +263,7 @@ void compute_mean(std::shared_ptr<const DefaultExecutor> exec,
             return x(i, j) * inv_total_size;
         },
         GKO_KERNEL_REDUCE_SUM(ValueType), result->get_values(), x->get_size(),
-        tmp, x, ValueType_nc{1.} / x->get_size()[0]);
+        tmp, x, ValueType_nc{1.} / std::max(1ul, x->get_size()[0]));
 }