diff --git a/README.md b/README.md
index 812c7dbad..99b3e7f03 100644
--- a/README.md
+++ b/README.md
@@ -71,6 +71,10 @@ Currently, the `@compat` macro supports the following syntaxes:
 * `@compat Array{<:Real}` and similar uses of `<:T` to define a set of parameterized types ([#20414]).
   In 0.4 and 0.5, this only works for non-nested usages (e.g. you can't define `Array{<:Array{<:Real}}`).
 
+* `@compat abstract type T end` and `@compat primitive type T 8 end`
+  to declare abstract and primitive types. [#20418]
+  This only work when `@compat` is applied directly on the declaration.
+
 ## Type Aliases
 
 * In 0.5, `ASCIIString` and `ByteString` were deprecated, and `UTF8String` was renamed to the (now concrete) type `String`.
diff --git a/src/Compat.jl b/src/Compat.jl
index 01c06a981..88411f2ef 100644
--- a/src/Compat.jl
+++ b/src/Compat.jl
@@ -746,8 +746,53 @@ function _compat(ex::Symbol)
 end
 _compat(ex) = ex
 
-macro compat(ex)
-    esc(_compat(ex))
+function _get_typebody(ex::Expr)
+    args = ex.args
+    if ex.head !== :type || length(args) != 3 || args[1] !== true
+        throw(ArgumentError("Invalid usage of @compat: $ex"))
+    end
+    name = args[2]
+    if !isexpr(args[3], :block)
+        throw(ArgumentError("Invalid type declaration: $ex"))
+    end
+    body = (args[3]::Expr).args
+    filter!(body) do e
+        if isa(e, LineNumberNode) || isexpr(e, :line)
+            return false
+        end
+        return true
+    end
+    return name, body
+end
+
+function _compat_primitive(typedecl)
+    name, body = _get_typebody(typedecl)
+    if length(body) != 1
+        throw(ArgumentError("Invalid primitive type declaration: $typedecl"))
+    end
+    return Expr(:bitstype, body[1], name)
+end
+
+function _compat_abstract(typedecl)
+    name, body = _get_typebody(typedecl)
+    if length(body) != 0
+        throw(ArgumentError("Invalid abstract type declaration: $typedecl"))
+    end
+    return Expr(:abstract, name)
+end
+
+macro compat(ex...)
+    if VERSION < v"0.6.0-dev.2746" && length(ex) == 2 && ex[1] === :primitive
+        return esc(_compat_primitive(ex[2]))
+    elseif length(ex) != 1
+        throw(ArgumentError("@compat called with wrong number of arguments: $ex"))
+    elseif (VERSION < v"0.6.0-dev.2746" && isexpr(ex[1], :abstract) &&
+            length(ex[1].args) == 1 && isexpr(ex[1].args[1], :type))
+        # This can in principle be handled in nested case but we do not
+        # do that to be consistent with primitive types.
+        return esc(_compat_abstract(ex[1].args[1]))
+    end
+    esc(_compat(ex[1]))
 end
 
 export @compat, @inline, @noinline
diff --git a/test/runtests.jl b/test/runtests.jl
index 97b9ddead..963216515 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -742,7 +742,7 @@ mktempdir() do dir
 
 
             verbose && println("$name read...")
-            @test @compat read(io()) == UInt8[convert(UInt8, _) for _ in text]
+            @test @compat read(io()) == UInt8[convert(UInt8, x) for x in text]
 
             @test read(io()) == read(filename)
 
@@ -843,7 +843,7 @@ mktempdir() do dir
         @test readstring("$filename.to") == text
 
         verbose && println("$name write(::IOBuffer, ...)")
-        @compat to = IOBuffer(UInt8[convert(UInt8, _) for _ in text], false, true)
+        @compat to = IOBuffer(UInt8[convert(UInt8, x) for x in text], false, true)
         write(to, io())
         @test String(take!(to)) == text
 
@@ -1353,8 +1353,10 @@ end
 end
 @test do_boundscheck() == true
 
-@test Compat.promote_eltype_op(@functorize(+), ones(2,2), 1) === Float64
-@test Compat.promote_eltype_op(@functorize(*), ones(Int, 2), zeros(Int16,2)) === Int
+if VERSION < v"0.6.0-dev.1886"
+    @test Compat.promote_eltype_op(@functorize(+), ones(2,2), 1) === Float64
+    @test Compat.promote_eltype_op(@functorize(*), ones(Int, 2), zeros(Int16,2)) === Int
+end
 
 #Add test for Base.normalize and Base.normalize!
 let
@@ -1622,7 +1624,7 @@ for x in (3.1, -17, 3//4, big(111.1), Inf)
 end
 
 # julia#20006
-abstract AbstractFoo20006
+@compat abstract type AbstractFoo20006 end
 immutable ConcreteFoo20006{T<:Int} <: AbstractFoo20006 end
 immutable ConcreteFoo20006N{T<:Int,N} <: AbstractFoo20006 end
 typealias ConcreteFoo200061{T<:Int} ConcreteFoo20006N{T,1}
@@ -1751,4 +1753,12 @@ end
 let x = [1,2,3]
     @dotcompat f(x) = x^2
     @test f(x) == [1,4,9]
-end
\ No newline at end of file
+end
+
+# PR #20418
+@compat abstract type Abstract20418{T} <: Ref{T} end
+@test Compat.TypeUtils.isabstract(Abstract20418)
+@compat primitive type Primitive20418{T} <: Ref{T} 16 end
+@test !Compat.TypeUtils.isabstract(Primitive20418)
+@test isbits(Primitive20418{Int})
+@test sizeof(Primitive20418{Int}) == 2