diff --git a/packaging/appimage/build.sh b/packaging/appimage/build.sh
index c0b815f..62dec9e 100755
--- a/packaging/appimage/build.sh
+++ b/packaging/appimage/build.sh
@@ -463,9 +463,15 @@ _compile_pywhispercpp_vulkan() {
        found {exit}' "$REPO_ROOT/requirements/vad.txt" > "$WORKDIR/pywhispercpp.txt"
   # Hosts that default cc/c++ to clang (this Cloud Agent image) fail the
   # CMAKE C++ compiler test: clang does not search gcc's libstdc++ path.
+  # GGML_NATIVE is ggml's default and compiles libggml-cpu with -march=native,
+  # tuned to whichever runner the build lands on. A runner with AVX-512 ships a
+  # libggml-cpu.so that dies with SIGILL on any CPU without it (#938), and the
+  # native cache then serves the same binary to every later build. OFF builds
+  # the portable baseline the PyPI wheel already ships; the Vulkan path is
+  # unaffected because its shaders run on the GPU.
   if ! CC="${CC:-gcc}" CXX="${CXX:-g++}" \
       GGML_VULKAN=1 \
-      CMAKE_ARGS="-DCMAKE_INSTALL_RPATH=\$ORIGIN -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON -DVulkan_INCLUDE_DIR=$VULKAN_INCLUDE_DIR" \
+      CMAKE_ARGS="-DCMAKE_INSTALL_RPATH=\$ORIGIN -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON -DGGML_NATIVE=OFF -DVulkan_INCLUDE_DIR=$VULKAN_INCLUDE_DIR" \
       uv_install --verbose --require-hashes --no-deps \
         --reinstall-package pywhispercpp --no-binary pywhispercpp \
         -r "$WORKDIR/pywhispercpp.txt" >"$pip_log" 2>&1; then
diff --git a/packaging/flatpak/python3-dependencies.yaml b/packaging/flatpak/python3-dependencies.yaml
index b6864fc..c6b484a 100644
--- a/packaging/flatpak/python3-dependencies.yaml
+++ b/packaging/flatpak/python3-dependencies.yaml
@@ -26,7 +26,12 @@ modules:
       # Assert the shape instead.
       - python3 -c "from pathlib import Path; p = Path('pywhispercpp-1.5.0/setup.py'); s = p.read_text(); n = 'setup(\\n    name=\"pywhispercpp\",'; assert n in s, 'pywhispercpp setup.py no longer matches the injection point'; p.write_text(s.replace(n, n + '\\n    version=\"1.5.0\",'))"
       - tar --owner=0 --group=0 -czf pywhispercpp-1.5.0.tar.gz pywhispercpp-1.5.0
-      - PYWHISPERCPP_VERSION=1.5.0 NO_REPAIR=1 GGML_VULKAN=1 pip3 install --verbose --exists-action=i --no-index --find-links="file://${PWD}"
+      # GGML_NATIVE is ggml's default and compiles libggml-cpu with
+      # -march=native, so the package inherits whichever instruction set the
+      # Flatpak builder has. An AVX-512 builder ships a binary that SIGILLs on
+      # any CPU without it (#938). OFF ships the portable baseline the PyPI
+      # wheel carries.
+      - PYWHISPERCPP_VERSION=1.5.0 NO_REPAIR=1 GGML_VULKAN=1 CMAKE_ARGS="-DGGML_NATIVE=OFF" pip3 install --verbose --exists-action=i --no-index --find-links="file://${PWD}"
         --prefix=${FLATPAK_DEST} "pywhispercpp" --no-build-isolation
       # whisper.cpp installs its shared libraries next to the extension module.
       # Symlink them onto the default loader path so the extension resolves them
diff --git a/tests/test_appimage_packaging.py b/tests/test_appimage_packaging.py
index 98b6b5f..3b5fc69 100644
--- a/tests/test_appimage_packaging.py
+++ b/tests/test_appimage_packaging.py
@@ -251,6 +251,21 @@ def test_vulkan_builds_against_pinned_headers_not_the_base_image_ones():
     ), "the rebuild does not point ggml at the pinned headers"
 
 
+def test_vulkan_rebuild_does_not_borrow_the_builders_instruction_set() -> None:
+    """GGML_NATIVE is ggml's default and puts -march=native on libggml-cpu, so
+    the AppImage inherits whichever instruction set the CI runner has. A runner
+    with AVX-512 ships a binary that SIGILLs on any CPU without it (#938), and
+    the shared native cache then serves the same one to every later build. OFF
+    matches the portable baseline the PyPI wheel falls back to."""
+    text = BUILD_SH.read_text(encoding="utf-8")
+    command_lines = [line for line in text.splitlines() if not line.lstrip().startswith("#")]
+    cmake_args = re.findall(r'CMAKE_ARGS="([^"]*)"', "\n".join(command_lines))
+    assert any("-DGGML_NATIVE=OFF" in args for args in cmake_args), (
+        "the Vulkan rebuild must not compile with -march=native; the AppImage"
+        " runs on CPUs the runner's instruction set does not describe"
+    )
+
+
 def test_vulkan_shaders_get_the_compiler_the_base_image_lacks():
     """ggml demands glslc specifically, and Ubuntu 22.04 packages none."""
     text = BUILD_SH.read_text(encoding="utf-8")
diff --git a/tests/test_flatpak_packaging.py b/tests/test_flatpak_packaging.py
index 649d614..c97a682 100644
--- a/tests/test_flatpak_packaging.py
+++ b/tests/test_flatpak_packaging.py
@@ -218,6 +218,25 @@ def test_the_version_injection_names_the_version_being_built() -> None:
     )
 
 
+def test_the_vulkan_build_does_not_borrow_the_builders_instruction_set() -> None:
+    """GGML_NATIVE is ggml's default and puts -march=native on libggml-cpu, so
+    the Flatpak inherits whichever instruction set the builder has, and the
+    result SIGILLs on any CPU without it (#938). OFF ships the portable
+    baseline the PyPI wheel carries."""
+    module = re.search(
+        r"^  - name: python3-pywhispercpp$(.*?)(?=^  - name: |\Z)",
+        DEPS_YAML.read_text(encoding="utf-8"),
+        re.M | re.S,
+    )
+    assert module, "the pywhispercpp module is gone; this test needs rewriting"
+    command_lines = [
+        line for line in module.group(1).splitlines() if not line.lstrip().startswith("#")
+    ]
+    assert any(
+        "-DGGML_NATIVE=OFF" in line and "pip3 install" in line for line in command_lines
+    ), "the Flatpak Vulkan build must not compile with -march=native"
+
+
 def test_the_manifest_env_agrees_with_the_module() -> None:
     """build-options.env sets PYWHISPERCPP_VERSION for the whole build. Left
     behind, it tells the build one version while the module builds another."""