diff --git a/REQUIRE b/REQUIRE
index 137767a..585e181 100644
--- a/REQUIRE
+++ b/REQUIRE
@@ -1 +1,3 @@
 julia 0.6
+Nullables 0.0.3
+Compat 0.33
diff --git a/src/ResultTypes.jl b/src/ResultTypes.jl
index a5778e5..66fc2b5 100644
--- a/src/ResultTypes.jl
+++ b/src/ResultTypes.jl
@@ -2,6 +2,8 @@ __precompile__()
 
 module ResultTypes
 
+using Nullables
+
 export Result, ErrorResult, unwrap, unwrap_error, iserror
 
 struct Result{T, E<:Exception}
@@ -20,7 +22,7 @@ function ErrorResult(::Type{T}, e::AbstractString="") where T
     Result{T, ErrorException}(Nullable{T}(), Nullable{ErrorException}(ErrorException(e)))
 end
 
-function unwrap{T, E}(r::Result{T, E})::T
+function unwrap(r::Result{T, E})::T where {T, E}
     if !isnull(r.result)
         return get(r.result)
     elseif !isnull(r.error)
@@ -30,7 +32,7 @@ function unwrap{T, E}(r::Result{T, E})::T
     end
 end
 
-function unwrap_error{T, E}(r::Result{T, E})::E
+function unwrap_error(r::Result{T, E})::E where {T, E}
     if !isnull(r.error)
         return get(r.error)
     else
@@ -38,7 +40,9 @@ function unwrap_error{T, E}(r::Result{T, E})::E
     end
 end
 
-Base.convert{T, S, E}(::Type{T}, r::Result{S, E})::T = unwrap(r)
+function Base.convert(::Type{T}, r::Result{S, E})::T where {T, S, E}
+    unwrap(r)
+end
 
 function Base.convert(::Type{Result{S, E}}, x::T) where {T, S, E}
     Result{S, E}(Nullable{S}(convert(S, x)), Nullable{E}())
diff --git a/test/runtests.jl b/test/runtests.jl
index 895703f..87fedb7 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,5 +1,8 @@
 using ResultTypes
-using Base.Test
+using Compat.Test
+using Nullables
+
+@testset "ResultTypes" begin
 
 @testset "Result" begin
     @testset "Basic result" begin
@@ -52,14 +55,14 @@ end
 @testset "Convert" begin
     @testset "From Result" begin
         x = Result(2)
-        @test Int(x) === 2
-        @test Float64(x) === 2.0
-        @test_throws MethodError String(x)
+        @test convert(Int, x) === 2
+        @test convert(Float64, x) === 2.0
+        @test_throws MethodError convert(String, x)
     end
 
     @testset "From ErrorResult" begin
         x = ErrorResult(Int, "Foo")
-        @test_throws ErrorException Int(x)
+        @test_throws ErrorException convert(Int, x)
     end
 
     @testset "To Result" begin
@@ -107,3 +110,5 @@ end
         @test isa(string(x), String)
     end
 end
+
+end