diff --git a/pkgs/development/tools/omniorb/default.nix b/pkgs/development/tools/omniorb/default.nix
index d9bca7061c1a..acc1dd1403dd 100644
--- a/pkgs/development/tools/omniorb/default.nix
+++ b/pkgs/development/tools/omniorb/default.nix
@@ -21,6 +21,21 @@ stdenv.mkDerivation rec {
   enableParallelBuilding = true;
   hardeningDisable = [ "format" ];
 
+  # Transform omniidl_be into a PEP420 namespace to allow other projects to define
+  # their omniidl backends. Especially useful for omniorbpy, the python backend.
+  postInstall = ''
+    rm $out/${python3.sitePackages}/omniidl_be/__init__.py
+    rm $out/${python3.sitePackages}/omniidl_be/__pycache__/__init__.*.pyc
+  '';
+
+  # Ensure postInstall didn't break cxx backend
+  # Same as 'pythonImportsCheck = ["omniidl_be.cxx"];', but outside buildPythonPackage
+  doInstallCheck = true;
+  postInstallCheck = ''
+    export PYTHONPATH=$out/${python3.sitePackages}:$PYTHONPATH
+    ${lib.getExe python3} -c "import omniidl_be.cxx"
+  '';
+
   meta = with lib; {
     description = "A robust high performance CORBA ORB for C++ and Python";
     longDescription = ''