diff --git a/Project.toml b/Project.toml
index daf8e7e..e367d8e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "TensorProducts"
 uuid = "decf83d6-1968-43f4-96dc-fdb3fe15fc6d"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.1.5"
+version = "0.1.6"
 
 [weakdeps]
 BlockArrays = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
diff --git a/src/onetoone.jl b/src/onetoone.jl
index a3bda64..ce86d9a 100644
--- a/src/onetoone.jl
+++ b/src/onetoone.jl
@@ -5,3 +5,6 @@ struct OneToOne{T} <: AbstractUnitRange{T} end
 OneToOne() = OneToOne{Int}()
 Base.first(a::OneToOne) = one(eltype(a))
 Base.last(a::OneToOne) = one(eltype(a))
+
+# impose Int64 to keep Base.to_shape(::Base.OneTo) convention
+Base.to_shape(::OneToOne) = 1
diff --git a/test/test_basics.jl b/test/test_basics.jl
index 745a2e8..c7597af 100644
--- a/test/test_basics.jl
+++ b/test/test_basics.jl
@@ -12,4 +12,6 @@ using TensorProducts: OneToOne
   @test length(a0) == 1
 
   @test blockaxes(OneToOne()) == (BlockRange(OneToOne()),)
+  @test Base.to_shape(OneToOne()) isa Int64
+  @test Base.to_shape(OneToOne()) == 1
 end