diff --git a/src/DiffOpt.jl b/src/DiffOpt.jl
index 71dd1a00..603031f6 100644
--- a/src/DiffOpt.jl
+++ b/src/DiffOpt.jl
@@ -15,6 +15,8 @@ import MathOptSetDistances as MOSD
 import ParametricOptInterface as POI
 import SparseArrays
 
+import Base.isempty
+
 include("utils.jl")
 include("product_of_sets.jl")
 include("diff_opt.jl")
diff --git a/src/diff_opt.jl b/src/diff_opt.jl
index 16c03a76..0b84f3e9 100644
--- a/src/diff_opt.jl
+++ b/src/diff_opt.jl
@@ -35,7 +35,7 @@ function Base.empty!(cache::InputCache)
     return
 end
 
-function isempty(cache::InputCache)
+function Base.isempty(cache::InputCache)
     return isempty(cache.dx) && isempty(cache.scalar_constraints) &&
         isempty(cache.vector_constraints) && cache.objective === nothing
 end