diff --git a/pkgs/applications/editors/yi/yi-custom-cabal/LICENSE b/pkgs/applications/editors/yi/yi-custom-cabal/LICENSE
new file mode 100644
index 000000000000..cf1ab25da034
--- /dev/null
+++ b/pkgs/applications/editors/yi/yi-custom-cabal/LICENSE
@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+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 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.
+
+For more information, please refer to <http://unlicense.org>
diff --git a/pkgs/applications/editors/yi/yi-custom-cabal/yi-custom.cabal b/pkgs/applications/editors/yi/yi-custom-cabal/yi-custom.cabal
new file mode 100644
index 000000000000..d9ffbb8e4817
--- /dev/null
+++ b/pkgs/applications/editors/yi/yi-custom-cabal/yi-custom.cabal
@@ -0,0 +1,17 @@
+name:           yi-custom
+version:        0.0.0.1
+category:       Yi
+synopsis:       Convenience wrapper for nix
+description:    Convenience wrapper for nix
+license:        PublicDomain
+license-file:   LICENSE
+author:         Mateusz Kowalczyk
+maintainer:     fuuzetsu@fuuzetsu.co.uk
+Cabal-Version:  >= 1.10
+build-type:     Simple
+
+library
+  hs-source-dirs: .
+  default-language: Haskell2010
+  build-depends: base, yi
+  ghc-options: -threaded
diff --git a/pkgs/applications/editors/yi/yi-custom.nix b/pkgs/applications/editors/yi/yi-custom.nix
new file mode 100644
index 000000000000..05b26f7046f2
--- /dev/null
+++ b/pkgs/applications/editors/yi/yi-custom.nix
@@ -0,0 +1,40 @@
+# This is a manually-written expression over an in-tree cabal file.
+# It's awkward but this way allows the package user to pass in
+# extraPackages without much extra hassle on their end, similarly how
+# the XMonad service handles it: the difference is that we don't have
+# anything like XMONAD_GHC…
+#
+# The idea is that the user changes their configs using any libraries
+# he likes and then builds it using this expression. Once that's done,
+# ‘reload’ and similar functions should all work as long as the user
+# doesn't need new libraries at which point they should add them to
+# extraPackages and rebuild from the expression.
+{ cabal, yi, extraPackages, makeWrapper }:
+
+cabal.mkDerivation (self: rec {
+  pname = "yi-custom";
+  version = "0.0.0.1";
+  src = ./yi-custom-cabal;
+  isLibrary = true;
+  buildDepends = extraPackages ++ [ yi ];
+  buildTools = [ makeWrapper ];
+  noHaddock = true;
+  doCheck = false;
+
+  # Allows Yi to find the libraries it needs at runtime. We drop ‘:’
+  # from this GHC_PACKAGE_PATH because we're wrapping over a different
+  # wrapper that used --prefix: if we didn't, we end up with a
+  # double-colon, confusing GHC.
+  postInstall = ''
+    makeWrapper ${yi}/bin/yi $out/bin/yi --set GHC_PACKAGE_PATH ''${GHC_PACKAGE_PATH%?}
+  '';
+
+  meta = {
+    homepage = "http://haskell.org/haskellwiki/Yi";
+    description = "Wrapper over user-specified Haskell libraries for use in Yi config";
+    license = self.stdenv.lib.licenses.publicDomain;
+    platforms = self.ghc.meta.platforms;
+    maintainers = with self.stdenv.lib.maintainers; [ fuuzetsu ];
+  };
+
+})
\ No newline at end of file
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 738884865a29..619c75effb3c 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -3090,10 +3090,16 @@ self : let callPackage = x : y : modifyPrio (newScope self x y); in
 
   wordTrie = callPackage ../development/libraries/haskell/word-trie {};
 
+  # You should prefer ‘yiCustom’ over ‘yi’ unless you never plan to
+  # use any external libraries in your config.
   yi = callPackage ../applications/editors/yi/yi.nix { };
 
   yiContrib = callPackage ../development/libraries/haskell/yi-contrib {};
 
+  yiCustom = callPackage ../applications/editors/yi/yi-custom.nix {
+    extraPackages = [];
+  };
+
   yiLanguage = callPackage ../development/libraries/haskell/yi-language {};
 
   yiRope = callPackage ../development/libraries/haskell/yi-rope {};