diff --git a/.github/workflows/build-xtgeo.yml b/.github/workflows/build-xtgeo.yml
new file mode 100644
index 000000000000..fd1df4aaadb2
--- /dev/null
+++ b/.github/workflows/build-xtgeo.yml
@@ -0,0 +1,128 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow is based on: https://github.com/equinor/xtgeo/blob/4.25.1/.github/workflows/publish.yml
+name: Build xtgeo wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version glob to (re)build; empty builds every version of docs/packages/xtgeo.yaml not released yet'
+        required: false
+        default: ''
+  pull_request:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-xtgeo.yml'
+      - 'docs/packages/xtgeo.yaml'
+  push:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-xtgeo.yml'
+      - 'docs/packages/xtgeo.yaml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+    with:
+      package: xtgeo
+      version: ${{ inputs.version }}
+
+  build_wheels:
+    needs: [setup]
+    if: needs.setup.outputs.versions != '[]'
+    name: Build xtgeo ${{ matrix.version }} ${{ matrix.python }}-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 90
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+        # Matches upstream's own matrix (cp311-cp314) minus cp311: numpy>=2.5
+        # sets 3.12 as its floor and our registry only hosts that line.
+        python:
+          - "cp312"
+          - "cp313"
+          - "cp314"
+
+    env:
+      XTGEO_VERSION: ${{ matrix.version }}
+
+    steps:
+      - name: Checkout xtgeo ${{ env.XTGEO_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: equinor/xtgeo
+          ref: ${{ env.XTGEO_VERSION }}
+          persist-credentials: false
+
+      - name: Checkout python-wheels
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      - name: Apply patches
+        run: git apply python-wheels/patches/xtgeo/${{ env.XTGEO_VERSION }}/*.patch
+
+      - name: Build wheels
+        uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        with:
+          output-dir: wheelhouse/
+          only: ${{ matrix.python }}-manylinux_riscv64
+        env:
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          # fmt-devel is EPEL-only and riscv64 has no EPEL; CMake fetches fmt instead.
+          CIBW_BEFORE_ALL_LINUX: yum install -y eigen3-devel
+          CIBW_BEFORE_BUILD: python -m pip install -U pip
+          # numpy has no riscv64 wheel on public PyPI; PIP_ONLY_BINARY keeps pip
+          # from source-building it (both for the build and for CIBW_TEST_COMMAND's
+          # test-extras install). pillow is listed too (gotcha 291): it's a
+          # transitive matplotlib dep, PyPI's newest pillow sdist has no riscv64
+          # wheel and fails to build from source (missing libjpeg headers in the
+          # manylinux image) - our own registry carries riscv64 pillow wheels.
+          CIBW_ENVIRONMENT: >-
+            PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/
+            PIP_ONLY_BINARY=numpy,pandas,scipy,pyarrow,h5py,hdf5plugin,matplotlib,segyio,shapely,pillow
+            SETUPTOOLS_SCM_PRETEND_VERSION_FOR_XTGEO=${{ env.XTGEO_VERSION }}
+          CIBW_TEST_EXTRAS: dev
+          CIBW_BEFORE_TEST: >-
+            pushd {package} &&
+            git clone --depth 1 https://github.com/equinor/xtgeo-testdata ../xtgeo-testdata || true
+          CIBW_TEST_COMMAND: >-
+            pushd {package} &&
+            pytest -n 4 tests --disable-warnings -m "not hypothesis" --ignore tests/test_well --ignore-glob="*forks.py"
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: xtgeo-${{ env.XTGEO_VERSION }}-${{ matrix.python }}-manylinux_riscv64
+          path: wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish xtgeo ${{ matrix.version }}
+    needs: [setup, build_wheels]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    secrets:
+      app-private-key: ${{ secrets.RISEPROJECT_APP_PRIVATE_KEY }}
+    with:
+      artifact-pattern: xtgeo-${{ matrix.version }}-*-manylinux_riscv64
diff --git a/docs/packages/xtgeo.yaml b/docs/packages/xtgeo.yaml
new file mode 100644
index 000000000000..16f61c7204aa
--- /dev/null
+++ b/docs/packages/xtgeo.yaml
@@ -0,0 +1,6 @@
+package-name: xtgeo
+source-code: https://github.com/equinor/xtgeo
+license: LGPL-3.0
+versions:
+- version: 4.25.1
+  patched: true
diff --git a/patches/xtgeo/4.25.1/0001-unpin-swig-for-riscv64.patch b/patches/xtgeo/4.25.1/0001-unpin-swig-for-riscv64.patch
new file mode 100644
index 000000000000..0709ec188a17
--- /dev/null
+++ b/patches/xtgeo/4.25.1/0001-unpin-swig-for-riscv64.patch
@@ -0,0 +1,34 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Tue, 13 Oct 2026 07:54:08 +0000
+Subject: [PATCH] unpin swig for riscv64
+
+pyproject.toml's build-system.requires pins "swig<4.3.0". PyPI's swig
+package only started publishing manylinux_riscv64 wheels at 4.3.1.post0,
+so pip falls back to building swig itself from its sdist on riscv64 for
+no reason that applies to this build: the pin (commit 839503b) exists to
+avoid a SWIG 4.3.0 numpy.i regression that segfaulted under Python 3.8 +
+pandas>2, and this release already requires Python >=3.11.
+
+Drop the pin so pip resolves swig 4.5.1, which ships a riscv64 wheel.
+
+Upstream-Status: Inappropriate [riscv64-only infra constraint; the pin's own Python 3.8 rationale no longer applies to this release]
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ pyproject.toml | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/pyproject.toml b/pyproject.toml
+index 718ff67..5b6f1cc 100644
+--- a/pyproject.toml
++++ b/pyproject.toml
+@@ -3,7 +3,7 @@ requires = [
+     "numpy>=2.0.0",
+     "pybind11",
+     "scikit-build-core[pyproject]>=0.10",
+-    "swig<4.3.0",
++    "swig",
+ ]
+ build-backend = "scikit_build_core.build"
+
diff --git a/patches/xtgeo/4.25.1/0002-fix-numpy-i-for-swig-4.3-appendoutput-signature.patch b/patches/xtgeo/4.25.1/0002-fix-numpy-i-for-swig-4.3-appendoutput-signature.patch
new file mode 100644
index 000000000000..ee2c36a27240
--- /dev/null
+++ b/patches/xtgeo/4.25.1/0002-fix-numpy-i-for-swig-4.3-appendoutput-signature.patch
@@ -0,0 +1,379 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Tue, 13 Oct 2026 08:08:08 +0000
+Subject: [PATCH] fix numpy.i for SWIG >=4.3's 3-arg SWIG_Python_AppendOutput
+
+SWIG 4.3.0 added an `is_void` third parameter to its generated
+SWIG_Python_AppendOutput() runtime helper (pyrun.swg). xtgeo's own
+project-local src/lib/numpy.i still calls it with the pre-4.3 two-arg
+form in every ARGOUT_ARRAY* typemap, so building with any SWIG >=4.3
+fails with "too few arguments to function 'SWIG_Python_AppendOutput'"
+-- reproduces on any arch, this host included.
+
+Call SWIG's SWIG_AppendOutput() macro instead, as numpy's own current
+tools/swig/numpy.i does. SWIG >=4.3 defines it as
+SWIG_Python_AppendOutput(result, obj, $isvoid) and older SWIG as the
+two-arg call, so it builds with any version. $isvoid matters: the
+helper only replaces a Py_None result when is_void is set, and a void
+C function's result starts as Py_None, so a hardcoded 0 would make
+every void function with ARGOUT arrays (grdcp3d_get_vtk_grid_arrays)
+return [None, a, b, c] instead of the pre-4.3 [a, b, c].
+
+This is required independently of which SWIG >=4.3 is used: swig<4.3
+has no riscv64 wheel on PyPI (gotcha territory -- see the companion
+0001 patch, which drops that pin), and 4.3.1.post0 (the first riscv64
+release) hits this same error.
+
+Upstream-Status: Inappropriate [riscv64 needs SWIG>=4.3.1.post0 for a PyPI wheel; this project-local numpy.i was never updated for SWIG 4.3's runtime signature change]
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ src/lib/numpy.i | 76 ++++++++++++++++++++++++-------------------------
+ 1 file changed, 38 insertions(+), 38 deletions(-)
+
+diff --git a/src/lib/numpy.i b/src/lib/numpy.i
+index b8fdaeb..60eb016 100644
+--- a/src/lib/numpy.i
++++ b/src/lib/numpy.i
+@@ -1988,7 +1988,7 @@
+ %typemap(argout)
+   (DATA_TYPE ARGOUT_ARRAY1[ANY])
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE* ARGOUT_ARRAY1, DIM_TYPE DIM1)
+@@ -2016,7 +2016,7 @@
+ %typemap(argout)
+   (DATA_TYPE* ARGOUT_ARRAY1, DIM_TYPE DIM1)
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE DIM1, DATA_TYPE* ARGOUT_ARRAY1)
+@@ -2044,7 +2044,7 @@
+ %typemap(argout)
+   (DIM_TYPE DIM1, DATA_TYPE* ARGOUT_ARRAY1)
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE ARGOUT_ARRAY2[ANY][ANY])
+@@ -2062,7 +2062,7 @@
+ %typemap(argout)
+   (DATA_TYPE ARGOUT_ARRAY2[ANY][ANY])
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE ARGOUT_ARRAY3[ANY][ANY][ANY])
+@@ -2080,7 +2080,7 @@
+ %typemap(argout)
+   (DATA_TYPE ARGOUT_ARRAY3[ANY][ANY][ANY])
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE ARGOUT_ARRAY4[ANY][ANY][ANY][ANY])
+@@ -2098,7 +2098,7 @@
+ %typemap(argout)
+   (DATA_TYPE ARGOUT_ARRAY4[ANY][ANY][ANY][ANY])
+ {
+-  $result = SWIG_Python_AppendOutput($result,(PyObject*)array$argnum);
++  $result = SWIG_AppendOutput($result,(PyObject*)array$argnum);
+ }
+ 
+ /*****************************/
+@@ -2123,7 +2123,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DATA_TYPE** ARGOUTVIEW_ARRAY1)
+@@ -2144,7 +2144,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_ARRAY2, DIM_TYPE* DIM1, DIM_TYPE* DIM2)
+@@ -2166,7 +2166,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DATA_TYPE** ARGOUTVIEW_ARRAY2)
+@@ -2188,7 +2188,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_FARRAY2, DIM_TYPE* DIM1, DIM_TYPE* DIM2)
+@@ -2210,7 +2210,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DATA_TYPE** ARGOUTVIEW_FARRAY2)
+@@ -2232,7 +2232,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_ARRAY3, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2256,7 +2256,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3,
+@@ -2280,7 +2280,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_FARRAY3, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2304,7 +2304,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3,
+@@ -2328,7 +2328,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_ARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2353,7 +2353,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -2378,7 +2378,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEW_FARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2403,7 +2403,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -2428,7 +2428,7 @@
+   PyArrayObject* array = (PyArrayObject*) obj;
+ 
+   if (!array || !require_fortran(array)) SWIG_fail;
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /*************************************/
+@@ -2466,7 +2466,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DATA_TYPE** ARGOUTVIEWM_ARRAY1)
+@@ -2500,7 +2500,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_ARRAY2, DIM_TYPE* DIM1, DIM_TYPE* DIM2)
+@@ -2535,7 +2535,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DATA_TYPE** ARGOUTVIEWM_ARRAY2)
+@@ -2570,7 +2570,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_FARRAY2, DIM_TYPE* DIM1, DIM_TYPE* DIM2)
+@@ -2605,7 +2605,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DATA_TYPE** ARGOUTVIEWM_FARRAY2)
+@@ -2640,7 +2640,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_ARRAY3, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2677,7 +2677,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3,
+@@ -2714,7 +2714,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_FARRAY3, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2751,7 +2751,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3,
+@@ -2788,7 +2788,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_ARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2826,7 +2826,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -2864,7 +2864,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_FARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2902,7 +2902,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -2940,7 +2940,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_ARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -2978,7 +2978,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -3016,7 +3016,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DATA_TYPE** ARGOUTVIEWM_FARRAY4, DIM_TYPE* DIM1, DIM_TYPE* DIM2,
+@@ -3054,7 +3054,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /* Typemap suite for (DIM_TYPE* DIM1, DIM_TYPE* DIM2, DIM_TYPE* DIM3, DIM_TYPE* DIM4,
+@@ -3092,7 +3092,7 @@
+   PyArray_SetBaseObject(array,cap);
+ %#endif
+ 
+-  $result = SWIG_Python_AppendOutput($result,obj);
++  $result = SWIG_AppendOutput($result,obj);
+ }
+ 
+ /**************************************/
diff --git a/patches/xtgeo/4.25.1/0003-fix-numpy-i-for-swig-4.5-removed-python2-macros.patch b/patches/xtgeo/4.25.1/0003-fix-numpy-i-for-swig-4.5-removed-python2-macros.patch
new file mode 100644
index 000000000000..e8a8cbcddff5
--- /dev/null
+++ b/patches/xtgeo/4.25.1/0003-fix-numpy-i-for-swig-4.5-removed-python2-macros.patch
@@ -0,0 +1,78 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Fri, 23 Oct 2026 16:30:00 +0000
+Subject: [PATCH] fix numpy.i for SWIG >=4.5's removed Python 2 macros
+
+SWIG 4.5.0 dropped the Python 2 compatibility macros from its
+pyhead.swg runtime, including PyString_Check, PyInt_Check and
+PyInt_AsLong. xtgeo's project-local src/lib/numpy.i still uses those
+three, so with SWIG >=4.5 the generated cxtgeoPYTHON_wrap.c calls
+undeclared functions: GCC 13 only warns, and the extension then fails
+to import with "undefined symbol: PyInt_AsLong"; GCC 14 rejects the
+implicit declarations outright. Reproduces on any arch.
+
+Replace each with the exact expansion SWIG <=4.4's pyhead.swg used on
+Python 3 (PyBytes_Check, PyLong_Check, PyLong_AsLong), so the generated
+code is unchanged for every SWIG version.
+
+Needed because 0001 drops the swig<4.3.0 pin, and pip then resolves
+the newest swig (4.5.1), which is the release with a riscv64 wheel.
+
+Upstream-Status: Inappropriate [only reachable once the swig<4.3.0 pin is dropped for riscv64; upstream's pinned SWIG still defines these macros]
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ src/lib/numpy.i | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+diff --git a/src/lib/numpy.i b/src/lib/numpy.i
+index 60eb016..ff3db39 100644
+--- a/src/lib/numpy.i
++++ b/src/lib/numpy.i
+@@ -112,8 +112,8 @@
+     if (py_obj == NULL          ) return "C NULL value";
+     if (py_obj == Py_None       ) return "Python None" ;
+     if (PyCallable_Check(py_obj)) return "callable"    ;
+-    if (PyString_Check(  py_obj)) return "string"      ;
+-    if (PyInt_Check(     py_obj)) return "int"         ;
++    if (PyBytes_Check(   py_obj)) return "string"      ;
++    if (PyLong_Check(    py_obj)) return "int"         ;
+     if (PyFloat_Check(   py_obj)) return "float"       ;
+     if (PyDict_Check(    py_obj)) return "dict"        ;
+     if (PyList_Check(    py_obj)) return "list"        ;
+@@ -1999,7 +1999,7 @@
+   (PyObject* array = NULL)
+ {
+   npy_intp dims[1];
+-  if (!PyInt_Check($input))
++  if (!PyLong_Check($input))
+   {
+     const char* typestring = pytype_string($input);
+     PyErr_Format(PyExc_TypeError,
+@@ -2007,7 +2007,7 @@
+                  typestring);
+     SWIG_fail;
+   }
+-  $2 = (DIM_TYPE) PyInt_AsLong($input);
++  $2 = (DIM_TYPE) PyLong_AsLong($input);
+   dims[0] = (npy_intp) $2;
+   array = PyArray_SimpleNew(1, dims, DATA_TYPECODE);
+   if (!array) SWIG_fail;
+@@ -2027,7 +2027,7 @@
+   (PyObject* array = NULL)
+ {
+   npy_intp dims[1];
+-  if (!PyInt_Check($input))
++  if (!PyLong_Check($input))
+   {
+     const char* typestring = pytype_string($input);
+     PyErr_Format(PyExc_TypeError,
+@@ -2035,7 +2035,7 @@
+                  typestring);
+     SWIG_fail;
+   }
+-  $1 = (DIM_TYPE) PyInt_AsLong($input);
++  $1 = (DIM_TYPE) PyLong_AsLong($input);
+   dims[0] = (npy_intp) $1;
+   array = PyArray_SimpleNew(1, dims, DATA_TYPECODE);
+   if (!array) SWIG_fail;