diff --git a/Project.toml b/Project.toml
index 9d2a73c..62cabc2 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ProblemReductions"
 uuid = "899c297d-f7d2-4ebf-8815-a35996def416"
 authors = ["GiggleLiu <cacate0129@gmail.com> and contributors"]
-version = "0.3.3"
+version = "0.3.4"
 
 [deps]
 BitBasis = "50ba71b6-fa0f-514d-ae9a-0916efc90dcf"
diff --git a/src/models/models.jl b/src/models/models.jl
index b39e352..df05165 100644
--- a/src/models/models.jl
+++ b/src/models/models.jl
@@ -311,7 +311,8 @@ The unit weight vector of length `n`.
 struct UnitWeight <: AbstractVector{Int}
     n::Int
 end
-Base.getindex(::UnitWeight, i) = 1
+Base.getindex(::UnitWeight, i::Integer) = 1
+Base.getindex(::UnitWeight, inds::AbstractVector) = UnitWeight(length(inds))
 Base.size(w::UnitWeight) = (w.n,)
 
 """
diff --git a/test/models/models.jl b/test/models/models.jl
index 13bb99f..37e80b9 100644
--- a/test/models/models.jl
+++ b/test/models/models.jl
@@ -6,6 +6,14 @@ using Test, ProblemReductions
     @test ProblemReductions.combinations(3, 2) == [[0, 0], [1, 0], [2, 0], [0, 1], [1, 1], [2, 1], [0, 2], [1, 2], [2, 2]]
 end
 
+@testset "UnitWeight" begin
+    w = UnitWeight(3)
+    @test w[1] == 1
+    @test w[2] == 1
+    @test w[3] == 1
+    @test w[1:2] === UnitWeight(2)
+end
+
 @testset "Circuit" begin
     include("Circuit.jl")
 end