diff --git a/Project.toml b/Project.toml
index 63eecba..888c22b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "Functors"
 uuid = "d9f16b24-f501-4c13-a1f2-28368ffc5196"
 authors = ["Mike J Innes <mike.j.innes@gmail.com>"]
-version = "0.5.0"
+version = "0.5.1"
 
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
diff --git a/docs/src/index.md b/docs/src/index.md
index c4dc636..9e5027b 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -62,6 +62,7 @@ Using [`@leaf`](@ref) instead of [`@functor`](@ref) will prevent the fields of a
 By default all composite types in are functors and can be traversed, unless marked with [`@leaf`](@ref). 
 
 The following types instead are explicitly marked as leaves in Functors.jl:
+- `Type`
 - `Number`.
 - `AbstractArray{<:Number}`, except for the wrappers `Transpose`, `Adjoint`, and `PermutedDimsArray`.
 - `AbstractRNG`.
diff --git a/src/base.jl b/src/base.jl
index b112c0d..7b8a3ad 100644
--- a/src/base.jl
+++ b/src/base.jl
@@ -2,6 +2,7 @@
 ### Opt-Out
 ###
 
+@leaf Type
 @leaf Number
 @leaf AbstractArray{<:Number}
 @leaf AbstractString
diff --git a/test/base.jl b/test/base.jl
index 5fd6466..918401e 100644
--- a/test/base.jl
+++ b/test/base.jl
@@ -211,4 +211,11 @@ end
   @test od2 isa OrderedDict
   @test od2[1] == 2
   @test od2[2] == 4
-end
\ No newline at end of file
+end
+
+@testset "Types are leaves" begin
+  @test Functors.isleaf(Int)
+  @test Functors.isleaf(Array)
+  @test fmap(identity, (1,Int,Ref,Array,5)) == (1,Int,Ref,Array,5)
+end
+