diff --git a/pkgs/applications/version-management/mercurial/4.9.nix b/pkgs/applications/version-management/mercurial/4.9.nix
new file mode 100644
index 00000000000..b8fc767bd3a
--- /dev/null
+++ b/pkgs/applications/version-management/mercurial/4.9.nix
@@ -0,0 +1,71 @@
+{ stdenv, fetchurl, python2Packages, makeWrapper, unzip
+, guiSupport ? false, tk ? null
+, ApplicationServices
+, mercurialSrc ? fetchurl rec {
+    meta.name = "mercurial-${meta.version}";
+    meta.version = "4.9.1";
+    url = "https://mercurial-scm.org/release/${meta.name}.tar.gz";
+    sha256 = "0iybbkd9add066729zg01kwz5hhc1s6lhp9rrnsmzq6ihyxj3p8v";
+  }
+}:
+
+let
+  inherit (python2Packages) docutils hg-git dulwich python;
+
+in python2Packages.buildPythonApplication {
+
+  inherit (mercurialSrc.meta) name version;
+  src = mercurialSrc;
+
+  format = "other";
+
+  inherit python; # pass it so that the same version can be used in hg2git
+
+  buildInputs = [ makeWrapper docutils unzip ]
+    ++ stdenv.lib.optionals stdenv.isDarwin [ ApplicationServices ];
+
+  propagatedBuildInputs = [ hg-git dulwich ];
+
+  makeFlags = [ "PREFIX=$(out)" ];
+
+  postInstall = (stdenv.lib.optionalString guiSupport
+    ''
+      mkdir -p $out/etc/mercurial
+      cp contrib/hgk $out/bin
+      cat >> $out/etc/mercurial/hgrc << EOF
+      [extensions]
+      hgk=$out/lib/${python.libPrefix}/site-packages/hgext/hgk.py
+      EOF
+      # setting HG so that hgk can be run itself as well (not only hg view)
+      WRAP_TK=" --set TK_LIBRARY ${tk}/lib/${tk.libPrefix}
+                --set HG $out/bin/hg
+                --prefix PATH : ${tk}/bin "
+    '') +
+    ''
+      for i in $(cd $out/bin && ls); do
+        wrapProgram $out/bin/$i \
+          $WRAP_TK
+      done
+
+      # copy hgweb.cgi to allow use in apache
+      mkdir -p $out/share/cgi-bin
+      cp -v hgweb.cgi contrib/hgweb.wsgi $out/share/cgi-bin
+      chmod u+x $out/share/cgi-bin/hgweb.cgi
+
+      # install bash/zsh completions
+      install -v -m644 -D contrib/bash_completion $out/share/bash-completion/completions/_hg
+      install -v -m644 -D contrib/zsh_completion $out/share/zsh/site-functions/_hg
+    '';
+
+  meta = {
+    inherit (mercurialSrc.meta) version;
+    description = "A fast, lightweight SCM system for very large distributed projects";
+    homepage = https://www.mercurial-scm.org;
+    downloadPage = https://www.mercurial-scm.org/release/;
+    license = stdenv.lib.licenses.gpl2;
+    maintainers = [ stdenv.lib.maintainers.eraserhd ];
+    updateWalker = true;
+    platforms = stdenv.lib.platforms.unix;
+  };
+}
+
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index d64fd48197b..f54db64d913 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -20063,6 +20063,9 @@ in
 
   menumaker = callPackage ../applications/misc/menumaker { };
 
+  mercurial_4 = callPackage ../applications/version-management/mercurial/4.9.nix {
+    inherit (darwin.apple_sdk.frameworks) ApplicationServices;
+  };
   mercurial = callPackage ../applications/version-management/mercurial {
     inherit (darwin.apple_sdk.frameworks) ApplicationServices;
   };