diff --git a/default.nix b/default.nix
index bdf5a7c..39c74ac 100644
--- a/default.nix
+++ b/default.nix
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: LicenseRef-Hippocratic-1.1
 
 let
-  pkgOverlay = self: super:
+  nativeOverlay = self: super:
     # Overlay of locally defined packages
     with self; {
       depot = callPackage ./depot { };
@@ -19,7 +19,7 @@ let
   toolchainOverlay = import ./toolchain-overlay;
   # Overlay of toolchain patches
 
-in { nixpkgs ? import ./nixpkgs.nix, nim-overlay ? <nim-overlay> }:
+in { nixpkgs ? ../nixpkgs, nim-overlay ? <nim-overlay>, extraOverlays ? [] }:
 
 import nixpkgs {
   # Evaluate an overlayed Nixpkgs for a Genode target
@@ -29,5 +29,5 @@ import nixpkgs {
     isGenode = true;
     imports = [ ./platform.nix ];
   };
-  overlays = [ toolchainOverlay (import nim-overlay) pkgOverlay ];
+  overlays = [ toolchainOverlay nativeOverlay (import nim-overlay) ] ++ extraOverlays;
 }
diff --git a/hydra/solo5.nix b/hydra/solo5.nix
index 782adf3..0c1e0b5 100644
--- a/hydra/solo5.nix
+++ b/hydra/solo5.nix
@@ -6,10 +6,6 @@
 , nim-overlay, prSrc }:
 
 let
-  release = import ../release.nix {
-    inherit dhall-haskell dhallNixpkgs dhallNixpkgsStaticLinux nixpkgs
-      genodepkgs nim-overlay;
-  };
 
   prOverride = attrs: {
     src = prSrc;
@@ -23,5 +19,15 @@ let
     '';
   };
 
-in
-{ build.x86_64.solo5 = pkgs.solo5.overrideAttrs prOverride; }
+  extraOverlays =
+    [ (self: super: { solo5 = super.solo5.overrideAttrs prOverride; }) ];
+
+  release = import ../release.nix {
+    inherit dhall-haskell dhallNixpkgs dhallNixpkgsStaticLinux nixpkgs
+      genodepkgs nim-overlay extraOverlays;
+  };
+
+in {
+  build.x86_64.solo5 = release.build.x86_64.solo5;
+  tests.x86_64.nova.solo5 = release.tests.x86_64.nova.solo5;
+}
diff --git a/release.nix b/release.nix
index ee5e940..5e92718 100644
--- a/release.nix
+++ b/release.nix
@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: LicenseRef-Hippocratic-1.1
 
-let dhallPinned = import ./dhallPinnedNixpkgs.nix; in
+let dhallPinned = import ../dhall-haskell/nix/pinnedNixpkgs.nix; in
 
 { genodepkgs ? ./default.nix
 , nixpkgs ? import ./nixpkgs.nix
@@ -10,10 +10,11 @@ let dhallPinned = import ./dhallPinnedNixpkgs.nix; in
 , dhallNixpkgs ? dhallPinned.nixpkgs
 , dhallNixpkgsStaticLinux ? dhallPinned.nixpkgsStaticLinux
 , nim-overlay ? <nim-overlay>
+, extraOverlays ? []
 }:
 
 let
-  pkgs = import genodepkgs { inherit nixpkgs nim-overlay; };
+  pkgs = import genodepkgs { inherit nixpkgs nim-overlay extraOverlays; };
   dhall-haskell' = import (dhall-haskell + "/release.nix") {
     nixpkgs = dhallNixpkgs;
     nixpkgsStaticLinux = dhallNixpkgsStaticLinux;