diff --git a/src/HalfIntegers.jl b/src/HalfIntegers.jl
index 0c1b427..2be62af 100644
--- a/src/HalfIntegers.jl
+++ b/src/HalfIntegers.jl
@@ -50,7 +50,7 @@ HalfInteger(x::BigFloat) = BigHalfInt(x)
         if isinteger(x)
             Base.unsafe_rational(tx >> 1, one(tx))
         else
-            Base.unsafe_rational(tx, oftype(tx, 2))
+            Base.unsafe_rational(tx, twice(one(tx)))
         end
     end
     function (::Type{Rational{T}})(x::HalfInteger) where T
@@ -58,11 +58,11 @@ HalfInteger(x::BigFloat) = BigHalfInt(x)
         if isinteger(x)
             Base.unsafe_rational(T, tx >> 1, one(tx))
         else
-            Base.unsafe_rational(T, tx, oftype(tx,2))
+            Base.unsafe_rational(T, tx, twice(one(tx)))
         end
     end
 else
-    (T::Type{<:Rational})(x::HalfInteger) = (tx=twice(x); T(tx,oftype(tx,2)))
+    (T::Type{<:Rational})(x::HalfInteger) = (tx=twice(x); T(tx,twice(one(tx))))
 end
 
 Base.ArithmeticStyle(::Type{<:HalfInteger}) = Base.ArithmeticWraps()
diff --git a/test/customtypes.jl b/test/customtypes.jl
index 6b19cd4..847a0dc 100644
--- a/test/customtypes.jl
+++ b/test/customtypes.jl
@@ -9,6 +9,13 @@ MyHalfInt(x::MyHalfInt) = x
 HalfIntegers.half(::Type{MyHalfInt}, x) = MyHalfInt(half(HalfInt, x))
 HalfIntegers.twice(x::MyHalfInt) = twice(x.val)
 
+struct One <: Integer end
+Base.promote_rule(::Type{One}, ::Type{T}) where {T<:Number} = promote_type(Bool, T)
+Base.Int(::One) = 1
+Base.iseven(::One) = false
+Base.one(::One) = One()
+Base.:+(x::One, y::One) = 2
+
 @testset "Custom types" begin
     @testset "Construction" begin
         @test MyHalfInt(2.5) isa MyHalfInt
@@ -35,6 +42,9 @@ HalfIntegers.twice(x::MyHalfInt) = twice(x.val)
         @test_throws InexactError Integer(MyHalfInt(3/2))
         @test_throws InexactError Int(MyHalfInt(3/2))
         @test_throws InexactError UInt(MyHalfInt(-1))
+
+        @test Rational(half(One())) == 1//2
+        @test Rational{Int}(half(One())) == 1//2
     end
 
     @testset "Properties" begin