diff --git a/src/attributes.jl b/src/attributes.jl
index 35d57fcc58..038a25903e 100644
--- a/src/attributes.jl
+++ b/src/attributes.jl
@@ -938,6 +938,7 @@ attributes that are modified by [`optimize!`](@ref).
 """
 is_set_by_optimize(::AnyAttribute) = false
 function is_set_by_optimize(::Union{ObjectiveValue,
+                                    DualObjectiveValue,
                                     ObjectiveBound,
                                     RelativeGap,
                                     SolveTime,