diff --git a/pkgs/applications/science/programming/scyther/cli.nix b/pkgs/applications/science/programming/scyther/cli.nix
deleted file mode 100644
index 0acf0989c636..000000000000
--- a/pkgs/applications/science/programming/scyther/cli.nix
+++ /dev/null
@@ -1,29 +0,0 @@
-{ stdenv, glibc, flex, bison, cmake
-, version, src, meta }:
-stdenv.mkDerivation {
-  pname = "scyther-cli";
-  inherit version;
-
-  inherit src meta;
-
-  nativeBuildInputs = [ cmake flex bison ];
-  buildInputs = [ glibc.static ];
-
-  patchPhase = ''
-    # Since we're not in a git dir, the normal command this project uses to create this file wouldn't work
-    printf "%s\n" "#define TAGVERSION \"${version}\"" > src/version.h
-  '';
-
-  configurePhase = ''
-    (cd src && cmakeConfigurePhase)
-  '';
-
-  dontUseCmakeBuildDir = true;
-  cmakeFlags = [ "-DCMAKE_C_FLAGS=-std=gnu89" ];
-
-  installPhase = ''
-    mkdir -p "$out/bin"
-    mv src/scyther-linux "$out/bin/scyther-cli"
-    ln -s "$out/bin/scyther-cli" "$out/bin/scyther-linux"
-  '';
-}
diff --git a/pkgs/applications/science/programming/scyther/default.nix b/pkgs/applications/science/programming/scyther/default.nix
deleted file mode 100644
index ca6b57de611d..000000000000
--- a/pkgs/applications/science/programming/scyther/default.nix
+++ /dev/null
@@ -1,80 +0,0 @@
-{ stdenv, lib, buildEnv, pkgsi686Linux, fetchFromGitHub, python27Packages, graphviz
-, includeGUI ? true
-, includeProtocols ? true
-}:
-let
-  version = "1.1.3";
-
-  src = fetchFromGitHub {
-    rev = "v${version}";
-    sha256 = "0rb4ha5bnjxnwj4f3hciq7kyj96fhw14hqbwl5kr9cdw8q62mx0h";
-    owner = "cascremers";
-    repo = "scyther";
-  };
-
-  meta = with lib; {
-    description = "A tool for the automatic verification of security protocols";
-    homepage = "https://www.cs.ox.ac.uk/people/cas.cremers/scyther/";
-    license = licenses.gpl2;
-    maintainers = with maintainers; [ infinisil ];
-    platforms = platforms.linux;
-  };
-
-  cli = pkgsi686Linux.callPackage ./cli.nix {
-    inherit version src meta;
-  };
-
-  gui = stdenv.mkDerivation {
-    pname = "scyther-gui";
-    inherit version;
-    inherit src meta;
-    buildInputs = [
-      python27Packages.wrapPython
-    ];
-
-    patchPhase = ''
-      file=gui/Scyther/Scyther.py
-
-      # By default the scyther binary is looked for in the directory of the python script ($out/gui), but we want to have it look where our cli package is
-      substituteInPlace $file --replace "return getMyDir()" "return \"${cli}/bin\""
-
-      # Removes the Shebang from the file, as this would be wrapped wrongly
-      sed -i -e "1d" $file
-    '';
-
-    dontBuild = true;
-
-    propagatedBuildInputs = [
-      python27Packages.wxPython
-      graphviz
-    ];
-
-    installPhase = ''
-      mkdir -p "$out"/gui "$out"/bin
-      cp -r gui/* "$out"/gui
-      ln -s "$out"/gui/scyther-gui.py "$out/bin/scyther-gui"
-    '';
-
-    postFixup = ''
-      wrapPythonProgramsIn "$out/gui" "$out $pythonPath"
-    '';
-
-    doInstallCheck = true;
-    installCheckPhase = ''
-      "$out/gui/scyther.py" "$src/gui/Protocols/Demo/ns3.spdl"
-    '';
-  };
-in
-  buildEnv {
-    name = "scyther-${version}";
-    inherit meta;
-    paths = [ cli ] ++ lib.optional includeGUI gui;
-    pathsToLink = [ "/bin" ];
-
-    postBuild = ''
-      rm "$out/bin/scyther-linux"
-    '' + lib.optionalString includeProtocols ''
-      mkdir -p "$out/protocols"
-      cp -rv ${src}/protocols/* "$out/protocols"
-    '';
-  }
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index cf33d0c52f2c..371cc3c0280b 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -839,6 +839,7 @@ mapAliases ({
   scaff = throw "scaff is deprecated - replaced by https://gitlab.com/jD91mZM2/inc (not in nixpkgs yet)"; # added 2020-03-01
   scim = sc-im; # added 2016-01-22
   scollector = bosun; # added 2018-04-25
+  scyther = throw "scyther has been removed since it currently only supports Python 2, see https://github.com/cascremers/scyther/issues/20"; # added 2021-10-07
   sdlmame = mame; # added 2019-10-30
   seeks = throw "seeks has been removed from nixpkgs, as it was unmaintained"; # added 2020-06-21
   seg3d = throw "seg3d has been removed from nixpkgs (2019-11-10)";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index a57a684905bc..836827921767 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -31592,8 +31592,6 @@ with pkgs;
 
   plm = callPackage ../applications/science/programming/plm { };
 
-  scyther = callPackage ../applications/science/programming/scyther { };
-
   ### SCIENCE/LOGIC
 
   abc-verifier = callPackage ../applications/science/logic/abc {};