diff --git a/AcmeMutablePackage.lhs b/AcmeMutablePackage.lhs
new file mode 100644
--- /dev/null
+++ b/AcmeMutablePackage.lhs
@@ -0,0 +1,15 @@
+> -- | This is a joke package. It is meant to show Haskell packages on
+> -- Hackage can be mutated by revising them. This package uses a custom
+> -- Cabal setup. It reads the package description, which is what you are
+> -- reading now, and creates a file at build time from its contents. Since
+> -- revisions are allowed to change descriptions, the package itself is
+> -- mutable. I personally disagree with Hackage revisions, so I authored
+> -- this package to show one way they can be abused.
+>
+> module AcmeMutablePackage ( mutable ) where
+>
+> -- | Are packages mutable? You might think they would be immutable, but you
+> -- would be wrong.
+>
+> mutable :: Bool
+> mutable = True
diff --git a/LICENSE.markdown b/LICENSE.markdown
new file mode 100644
--- /dev/null
+++ b/LICENSE.markdown
@@ -0,0 +1,23 @@
+# [The MIT License (MIT)][]
+
+Copyright (c) Taylor Fausak
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+[The MIT License (MIT)]: http://opensource.org/licenses/MIT
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,12 @@
+import Distribution.PackageDescription.Parse
+import Distribution.Simple
+import Distribution.Types.GenericPackageDescription
+import Distribution.Types.PackageDescription
+
+main :: IO ()
+main = defaultMainWithHooks simpleUserHooks
+  { preBuild = \ args flags -> do
+    package <- readGenericPackageDescription minBound "acme-mutable-package.cabal"
+    writeFile "AcmeMutablePackage.lhs" (description (packageDescription package))
+    preBuild simpleUserHooks args flags
+  }
diff --git a/acme-mutable-package.cabal b/acme-mutable-package.cabal
new file mode 100644
--- /dev/null
+++ b/acme-mutable-package.cabal
@@ -0,0 +1,42 @@
+name: acme-mutable-package
+version: 0
+
+build-type: Custom
+cabal-version: >= 1.6
+category: ACME
+license: MIT
+license-file: LICENSE.markdown
+maintainer: Taylor Fausak
+
+synopsis: A mutable package.
+description:
+  > -- | This is a joke package. It is meant to show Haskell packages on
+  > -- Hackage can be mutated by revising them. This package uses a custom
+  > -- Cabal setup. It reads the package description, which is what you are
+  > -- reading now, and creates a file at build time from its contents. Since
+  > -- revisions are allowed to change descriptions, the package itself is
+  > -- mutable. I personally disagree with Hackage revisions, so I authored
+  > -- this package to show one way they can be abused.
+  >
+  > module AcmeMutablePackage ( mutable ) where
+  >
+  > -- | Are packages mutable? You might think they would be immutable, but you
+  > -- would be wrong.
+  >
+  > mutable :: Bool
+  > mutable = True
+
+source-repository head
+  type: git
+  location: https://github.com/tfausak/acme-mutable-package
+
+custom-setup
+  setup-depends:
+    base >= 4.10.1 && < 4.11,
+    Cabal >= 2.0.1 && < 2.1
+
+library
+  build-depends:
+    base >= 4.10.1 && < 4.11
+  exposed-modules:
+    AcmeMutablePackage