diff --git a/.github/workflows/build-appimage.yml b/.github/workflows/build-appimage.yml
index bd24143f..ccc3e37b 100644
--- a/.github/workflows/build-appimage.yml
+++ b/.github/workflows/build-appimage.yml
@@ -51,6 +51,9 @@ jobs:
         env:
           # appimagetool runs without FUSE on CI runners
           APPIMAGE_EXTRACT_AND_RUN: '1'
+          # Keep AppImages compatible with distributions that provide glibc
+          # 2.36. The build script rejects artifacts linked against newer versions.
+          MAX_GLIBC_VERSION: '2.36'
           PYTHON: python
         run: ./packaging/linux/build_appimage.sh
 
diff --git a/Module/appconfig.py b/Module/appconfig.py
index c5f6eb02..c44aee14 100644
--- a/Module/appconfig.py
+++ b/Module/appconfig.py
@@ -84,6 +84,25 @@ def write_openkh_path(selected_directory):
     update_app_config('openkh_folder', selected_directory)
 
 
+def is_openkh_folder(selected_path: Path) -> bool:
+    """Accept both extracted OpenKH installations and Linux config folders."""
+    mods_manager_names = (
+        "OpenKh.Tools.ModsManager.exe",
+        "OpenKh.Tools.ModsManager",
+        "OpenKh.Tools.ModsManager.Avalonia",
+    )
+    tool_directories = (selected_path, selected_path / "Apps")
+    has_mods_manager = any(
+        (tool_directory / name).is_file()
+        for tool_directory in tool_directories
+        for name in mods_manager_names
+    )
+
+    # Native Linux installations keep Mods Manager data in ~/.config/OpenKh.
+    has_mods_manager_config = (selected_path / "mods-manager.yml").is_file()
+    return has_mods_manager or has_mods_manager_config
+
+
 def read_custom_music_path() -> Optional[Path]:
     return _read_directory("custom_music_folder")
 
diff --git a/UI/configui.py b/UI/configui.py
index c0377f00..7c6d09fc 100644
--- a/UI/configui.py
+++ b/UI/configui.py
@@ -20,17 +20,12 @@ def openkh_folder_getter() -> bool:
         return False
 
     selected_path = Path(selected_directory)
-    mods_manager_names = (
-        "OpenKh.Tools.ModsManager.exe",
-        "OpenKh.Tools.ModsManager",
-        "OpenKh.Tools.ModsManager.Avalonia",
-    )
-    if not any((selected_path / name).is_file() for name in mods_manager_names):
+    if not appconfig.is_openkh_folder(selected_path):
         show_alert("Not a valid OpenKH folder.")
         return False
-    else:
-        appconfig.write_openkh_path(selected_directory)
-        return True
+
+    appconfig.write_openkh_path(selected_directory)
+    return True
 
 
 def custom_music_folder_getter() -> bool:
diff --git a/packaging/linux/build_appimage.sh b/packaging/linux/build_appimage.sh
index 8d1224a9..f3e178b6 100755
--- a/packaging/linux/build_appimage.sh
+++ b/packaging/linux/build_appimage.sh
@@ -18,6 +18,7 @@ BUILD_DIR=build/appimage
 APPDIR="$BUILD_DIR/AppDir"
 OUTPUT_NAME="KH2.Randomizer-x86_64.AppImage"
 APPIMAGETOOL_SHA256="a6d71e2b6cd66f8e8d16c37ad164658985e0cf5fcaa950c90a482890cb9d13e0"
+MAX_GLIBC_VERSION=${MAX_GLIBC_VERSION:-2.36}
 
 if [ ! -f extracted_data.zip ]; then
     echo "error: extracted_data.zip not found in the repo root (required for bundling)" >&2
@@ -34,6 +35,10 @@ cp packaging/linux/kh2randomizer.desktop "$APPDIR/"
 "$PYTHON" -c "from PIL import Image; Image.open('rando.ico').save('$APPDIR/kh2randomizer.png')"
 cp "$APPDIR/kh2randomizer.png" "$APPDIR/usr/share/icons/hicolor/256x256/apps/kh2randomizer.png"
 
+# Fail before packaging if a local or CI build accidentally raises the Linux
+# runtime requirement above the compatibility target.
+packaging/linux/check_glibc_compatibility.sh "$APPDIR" "$MAX_GLIBC_VERSION"
+
 APPIMAGETOOL=${APPIMAGETOOL:-appimagetool}
 if ! command -v "$APPIMAGETOOL" >/dev/null 2>&1; then
     APPIMAGETOOL="$BUILD_DIR/appimagetool-x86_64.AppImage"
diff --git a/packaging/linux/check_glibc_compatibility.sh b/packaging/linux/check_glibc_compatibility.sh
new file mode 100755
index 00000000..f7022c4c
--- /dev/null
+++ b/packaging/linux/check_glibc_compatibility.sh
@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# Verifies that every ELF binary in a directory supports the requested glibc.
+set -euo pipefail
+
+ROOT=${1:?usage: check_glibc_compatibility.sh DIRECTORY [MAX_GLIBC_VERSION]}
+MAX_GLIBC_VERSION=${2:-2.36}
+highest_version=0
+highest_file=
+
+while IFS= read -r -d '' file; do
+    if ! readelf -h "$file" >/dev/null 2>&1; then
+        continue
+    fi
+
+    version=$(readelf --version-info "$file" 2>/dev/null \
+        | grep -oE 'GLIBC_[0-9]+\.[0-9]+' \
+        | sed 's/^GLIBC_//' \
+        | sort -V \
+        | tail -n 1 || true)
+
+    if [ -n "$version" ] && [ "$(printf '%s\n%s\n' "$highest_version" "$version" | sort -V | tail -n 1)" = "$version" ]; then
+        highest_version=$version
+        highest_file=$file
+    fi
+done < <(find "$ROOT" -type f -print0)
+
+echo "Highest required glibc version: $highest_version${highest_file:+ ($highest_file)}"
+
+if [ "$(printf '%s\n%s\n' "$MAX_GLIBC_VERSION" "$highest_version" | sort -V | tail -n 1)" != "$MAX_GLIBC_VERSION" ]; then
+    echo "error: build requires glibc $highest_version, newer than supported glibc $MAX_GLIBC_VERSION" >&2
+    exit 1
+fi
diff --git a/tests/test_configui.py b/tests/test_configui.py
new file mode 100644
index 00000000..0aca5660
--- /dev/null
+++ b/tests/test_configui.py
@@ -0,0 +1,19 @@
+from Module import appconfig
+
+
+def test_openkh_folder_accepts_linux_config_directory(tmp_path):
+    (tmp_path / "mods-manager.yml").write_text("installedModsPath: /tmp/mods\n")
+
+    assert appconfig.is_openkh_folder(tmp_path)
+
+
+def test_openkh_folder_accepts_mods_manager_in_apps(tmp_path):
+    apps_path = tmp_path / "Apps"
+    apps_path.mkdir()
+    (apps_path / "OpenKh.Tools.ModsManager").write_text("tool")
+
+    assert appconfig.is_openkh_folder(tmp_path)
+
+
+def test_openkh_folder_rejects_unrelated_directory(tmp_path):
+    assert not appconfig.is_openkh_folder(tmp_path)