diff --git a/nix-builder/lib/extension/torch/arch.nix b/nix-builder/lib/extension/torch/arch.nix
index e9fbb322..e37ef6a8 100644
--- a/nix-builder/lib/extension/torch/arch.nix
+++ b/nix-builder/lib/extension/torch/arch.nix
@@ -123,6 +123,8 @@ let
 
   metalSupport = buildConfig.metal or false;
 
+  cpuSupport = buildConfig.cpu or false;
+
   provenanceFlags = import ../provenance-flags.nix { inherit lib kernelProvenance; };
 
 in
@@ -281,17 +283,26 @@ stdenv.mkDerivation (prevAttrs: {
   ]
   ++ lib.optionals cudaSupport [
     (lib.cmakeFeature "CMAKE_CUDA_HOST_COMPILER" "${stdenv.cc}/bin/g++")
+    (lib.cmakeFeature "GPU_LANG" "CUDA")
   ]
   ++ lib.optionals rocmSupport [
     # Ensure sure that we use HIP from our CLR override and not HIP from
     # the symlink-joined ROCm toolkit.
     (lib.cmakeFeature "CMAKE_HIP_COMPILER_ROCM_ROOT" "${clr}")
     (lib.cmakeFeature "HIP_ROOT_DIR" "${clr}")
+    (lib.cmakeFeature "GPU_LANG" "HIP")
   ]
   ++ lib.optionals metalSupport [
     # Use host compiler for Metal. Not included in the redistributable SDK.
     # Re-enable when the issue mentioned in preConfigure is solved.
     #(lib.cmakeFeature "METAL_COMPILER" "${xcrunHost}/bin/xcrunHost")
+    (lib.cmakeFeature "GPU_LANG" "METAL")
+  ]
+  ++ lib.optionals xpuSupport [
+    (lib.cmakeFeature "GPU_LANG" "SYCL")
+  ]
+  ++ lib.optionals cpuSupport [
+    (lib.cmakeFeature "GPU_LANG" "CPU")
   ];
 
   postInstall = ''
diff --git a/nix-builder/tests/Dockerfile.test-kernel b/nix-builder/tests/Dockerfile.test-kernel
index d53c8668..1ce2a5bd 100644
--- a/nix-builder/tests/Dockerfile.test-kernel
+++ b/nix-builder/tests/Dockerfile.test-kernel
@@ -15,8 +15,10 @@ ENV DEBIAN_FRONTEND=noninteractive \
     NVIDIA_DRIVER_CAPABILITIES=compute,utility
 
 # Install uv and Rust toolchain (Rust is needed to build kernels from source, which
-# bundles a maturin/pyo3 extension module).
-RUN dnf install -y --allowerasing curl && \
+# bundles a maturin/pyo3 extension module). We disable the CUDA repo, because we
+# don't need it for curl and it reduces the chance of transient errors when
+# installing.
+RUN dnf install -y --allowerasing --disablerepo=cuda curl && \
     curl -LsSf https://astral.sh/uv/install.sh | sh && \
     curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y && \
     dnf clean all