diff --git a/k/default.nix b/k/default.nix
new file mode 100644
index 0000000..76acd1d
--- /dev/null
+++ b/k/default.nix
@@ -0,0 +1,34 @@
+{ stdenv, fetchurl }:
+
+assert stdenv.is64bit;
+assert stdenv.isLinux || stdenv.isDarwin;
+
+let
+    osdir = if stdenv.isDarwin then "osx-64" else "linux-64";
+    sha256 = if stdenv.isDarwin
+             then "e50e84a017a585f9459302ce2670c04385e1f59adcacc3ecdecad79edce6ed07"
+             else "6c4b776e85fe04d8efb178ccc9278bd5ee31d57b11e23886226564cdc8677d06";
+in stdenv.mkDerivation rec {
+    name = "k";
+    version = "2019.03.21-1047_g7948682";
+    src = fetchurl {
+        inherit sha256;
+        url = "https://anaconda.org/shaktidb/shakti/${builtins.substring 0 10 version}/download/${osdir}/shakti-${version}.tar.bz2";
+    };
+    phases = [ "installPhase" ];
+    installPhase = ''
+        mkdir -p "$out"
+        tar -xf "${src}" -C "$out" "bin/${name}"
+        chmod +x "$out/bin/${name}"
+    '';
+    meta = with stdenv.lib; {
+        description = "An interpreter for the k7 language.";
+        license = {
+            fullName = "Evaluation Agreement";
+            url = https://shakti.com/license;
+            free = false;
+        };
+        homepage = https://shakti.com/;
+        platforms = with platforms; linux ++ darwin;
+    };
+}
diff --git a/sourcetrail/default.nix b/sourcetrail/default.nix
deleted file mode 100644
index 9aa8cf0..0000000
--- a/sourcetrail/default.nix
+++ /dev/null
@@ -1,50 +0,0 @@
-{lib, stdenv, pkgs, fetchurl, buildFHSUserEnv}:
-let 
-    libPath = lib.makeLibraryPath (with pkgs; [
-            zlib
-            expat
-    ]);
-
-    sourcetrail = stdenv.mkDerivation rec {
-        name = "sourcetrail-${version}";
-        version = "2018.2.77";
-
-        src = fetchurl {
-            name = "${name}.tar.gz";
-            url = "https://www.sourcetrail.com/downloads/${version}/linux/64bit";
-            sha256 = "1edfe95818f656840640d360df0cee72944af668d09b1a83cb6cb967ccaee719";
-            sha512 = "667b45449689d8f22a2a3ab2b9ad5d7d0c919fa61701e164927624df8843804b7b3f4c19e38e41da4afcff892a464157bea4cbffaa38e529bda364d1c284ee52";
-        };
-
-        phases = [ "unpackPhase" "installPhase" ];
-
-        installPhase = ''
-            mkdir -p $out/{opt/sourcetrail,usr,bin}
-            rm install.sh uninstall.sh
-            mv setup/share $out/usr/
-            mv * $out/opt/sourcetrail/
-
-            substituteInPlace $out/usr/share/applications/sourcetrail.desktop --replace '/usr/bin' "$out/bin"
-
-            for exe in $out/opt/sourcetrail/{Sourcetrail,sourcetrail_indexer}; do
-                patchelf \
-                    --set-interpreter "${stdenv.cc.bintools.dynamicLinker}" \
-                    $exe
-            done
-
-            ln -s $out/opt/sourcetrail/Sourcetrail.sh $out/bin/sourcetrail
-        '';
-    };
-in buildFHSUserEnv rec {
-    name = sourcetrail.name;
-
-    profile = "LD_LIBRARY_PATH=${libPath}:$LD_LIBRARY_PATH";
-    targetPkgs = pkgs: [ sourcetrail ];
-    runScript = "sourcetrail";
-
-    meta = with lib; {
-        description = "A cross-platform source explorer for C/C++ and Java.";
-        homepage = https://www.sourcetrail.com;
-        license = licenses.unfree; # :(
-    };
-}