diff --git a/README.md b/README.md
index 3b52c175f..407ebd69a 100644
--- a/README.md
+++ b/README.md
@@ -143,6 +143,10 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `remotecall`, `remotecall_fetch`, `remotecall_wait`, and `remote_do` have the function to be executed remotely as the first argument in Julia 0.5. Loading `Compat` defines the same methods in older versions of Julia. [#13338](https://github.com/JuliaLang/julia/pull/13338)
 
+* `Base.FS` is now `Base.Filesystem` [#12819](https://github.com/JuliaLang/julia/pull/12819).
+  Compat provides an unexported `Compat.Filesystem` method that is aliased to
+  `Base.FS` on Julia 0.3 and 0.4 and `Base.Filesystem` on Julia 0.5.
+
 ## New types
 
 * [`Nullable` types](http://julia.readthedocs.org/en/latest/manual/types/?highlight=nullable#nullable-types-representing-missing-values) and their associated operations.
diff --git a/src/Compat.jl b/src/Compat.jl
index 8ea6bae76..ebee193a6 100644
--- a/src/Compat.jl
+++ b/src/Compat.jl
@@ -706,4 +706,10 @@ if VERSION < v"0.5.0-dev+763"
     const SparseArrays = Base.SparseMatrix
 end
 
+if VERSION < v"0.5.0-dev+1229"
+    const Filesystem = FS
+else
+    import Base.Filesystem
+end
+
 end # module
diff --git a/test/runtests.jl b/test/runtests.jl
index 500d40e4f..21f760c94 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -545,3 +545,6 @@ Base.remote_do(() -> true, 1) # Doesn't return anything so cannot be `@test`ed b
 
 # JuliaLang/julia#13440
 @test isa(SparseArrays, Module)
+
+# JuliaLang/julia#12819
+@test Compat.Filesystem.JL_O_RDWR == Compat.Filesystem.JL_O_RDWR