diff --git a/packages/default.nix b/packages/default.nix
index 6eb9625..14d9e09 100644
--- a/packages/default.nix
+++ b/packages/default.nix
@@ -51,4 +51,11 @@ in upstream // {
 
   stdcxx = callPackage ./stdcxx { };
 
+  worldSources = buildPackages.fetchFromGitHub {
+    owner = "genodelabs";
+    repo = "genode-world";
+    rev = "521f9fb5a66b18441f53a96e3993a84b772f27e5";
+    sha256 = "0dy906ffbw6khkwd05vhppcw2mr4ma0h3b6n52a71cfail87jfnw";
+  };
+
 }
diff --git a/packages/genodelabs/default.nix b/packages/genodelabs/default.nix
index 91d9e3e..8b44ad2 100644
--- a/packages/genodelabs/default.nix
+++ b/packages/genodelabs/default.nix
@@ -57,14 +57,14 @@ let
     # Prepare a "port" of source code declared in the Genode sources
     name:
     { hash ? "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
-    , patches ? [ ], ... }@args:
+    , patches ? [ ], extraRepos ? [ ], ... }@args:
     let
-      havePatches = patches != [ ];
-      version = portVersions.${name};
+      dontUnpack = patches == [ ] && extraRepos == [ ];
+      version = portVersions.${name} or args.version;
     in with buildPackages.buildPackages;
     stdenvNoCC.mkDerivation (args // {
       name = name + "-port-" + version;
-      inherit version patches;
+      inherit version patches dontUnpack extraRepos;
       preferLocalBuild = true;
       outputHashMode = "recursive";
       outputHash = hash;
@@ -76,8 +76,7 @@ let
       impureEnvVars = lib.fetchers.proxyImpureEnvVars
         ++ [ "GIT_PROXY_COMMAND" "SOCKS_SERVER" ];
 
-      src = if havePatches then genodeSources else null;
-      dontUnpack = !havePatches;
+      src = if dontUnpack then null else genodeSources;
 
       dontConfigure = true;
 
@@ -90,7 +89,10 @@ let
         ''
           runHook preBuild
           export CONTRIB_DIR=$NIX_BUILD_TOP/contrib
-          export GENODE_DIR=${if havePatches then "$(pwd)" else genodeSources}
+          export GENODE_DIR=${if dontUnpack then genodeSources else "$(pwd)"}
+          for repo in $extraRepos; do
+            ln -s $repo $GENODE_DIR/repos/
+          done
           mkdir $CONTRIB_DIR
           $GENODE_DIR/tool/ports/prepare_port ${name} CHECK_HASH=no
           runHook postBuild
@@ -116,7 +118,9 @@ let
     });
 
   ports = lib.mapAttrs preparePort (import ./ports.nix {
-    pkgs = flake.inputs.nixpkgs.legacyPackages.x86_64-linux;
+    pkgs = flake.inputs.nixpkgs.legacyPackages.x86_64-linux // {
+      inherit (pkgs) genodePackages;
+    };
   });
   # The "ports" mechanism is hardly deterministic, so prepare with
   # a pinned nixpkgs revision for a pinned platform.