diff --git a/pkgs/applications/audio/ardour/default.nix b/pkgs/applications/audio/ardour/default.nix
index 2338af6ec99..e47dbfb856b 100644
--- a/pkgs/applications/audio/ardour/default.nix
+++ b/pkgs/applications/audio/ardour/default.nix
@@ -15,11 +15,7 @@ let
   # "git describe" when _not_ on an annotated tag(!): MAJOR.MINOR-REV-HASH.
 
   # Version to build.
-  tag = "4.1";
-
-  # Version info that is built into the binary. Keep in sync with 'tag'. The
-  # last 8 digits is a (fake) commit id.
-  revision = "4.1-fe672c8";
+  tag = "4.2";
 
 in
 
@@ -42,7 +38,7 @@ stdenv.mkDerivation rec {
     ];
 
   patchPhase = ''
-    printf '#include "libs/ardour/ardour/revision.h"\nnamespace ARDOUR { const char* revision = \"${revision}\"; }\n' > libs/ardour/revision.cc
+    printf '#include "libs/ardour/ardour/revision.h"\nnamespace ARDOUR { const char* revision = \"${tag}-${builtins.substring 0 8 src.rev}\"; }\n' > libs/ardour/revision.cc
     sed 's|/usr/include/libintl.h|${glibc}/include/libintl.h|' -i wscript
     patchShebangs ./tools/
   '';
diff --git a/pkgs/applications/audio/rkrlv2/default.nix b/pkgs/applications/audio/rkrlv2/default.nix
new file mode 100644
index 00000000000..9c41c88b012
--- /dev/null
+++ b/pkgs/applications/audio/rkrlv2/default.nix
@@ -0,0 +1,24 @@
+{ stdenv, pkgs, fetchFromGitHub,
+automake, pkgconfig, lv2, fftw, cmake, xlibs, libjack2, libsamplerate, libsndfile
+}:
+
+stdenv.mkDerivation rec {
+  repo = "rkrlv2";
+  name = "${repo}-b1.0";
+
+  src = fetchFromGitHub {
+    owner = "ssj71";
+    inherit repo;
+    rev = "a315f5aefe63be7e34663596b8b050410a9b7e72";
+    sha256 = "0kr3rvq7n1bh47qryyarcpiibms601qd8l1vypmm61969l4d4bn8";
+  };
+
+  buildInputs = with xlibs; [ automake pkgconfig lv2 fftw cmake libXpm libjack2 libsamplerate libsndfile libXft ];
+
+  meta = {
+    description = "Rakarrak effects ported to LV2";
+    homepage = https://github.com/ssj71/rkrlv2;
+    license = stdenv.lib.licenses.gpl3;
+    maintainers = [ stdenv.lib.maintainers.joelmo ];
+  };
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 4bec3213522..26f1c0b0306 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -398,7 +398,7 @@ let
     inherit name sha256;
     url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz";
     meta.homepage = "https://github.com/${owner}/${repo}/";
-  };
+  } // { inherit rev; };
 
   fetchFromBitbucket = { owner, repo, rev, sha256, name ? "${repo}-${rev}-src" }: fetchzip {
     inherit name sha256;
@@ -2852,6 +2852,8 @@ let
 
   rkflashtool = callPackage ../tools/misc/rkflashtool { };
 
+  rkrlv2 = callPackage ../applications/audio/rkrlv2 {};
+
   rmlint = callPackage ../tools/misc/rmlint {
     inherit (pythonPackages) sphinx;
   };