diff --git a/test-all-native.sh b/test-all-native.sh
index c60e18c..07da893 100755
--- a/test-all-native.sh
+++ b/test-all-native.sh
@@ -41,10 +41,12 @@ kinematics_unknown_filter_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_kinematics_manif
 kinematics_unknown_output_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_kinematics_manifest_unknown_output.XXXXXX.log")
 inputs_cached_missing_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_inputs_cached_missing_cache_dir.XXXXXX.log")
 inputs_cached_whitespace_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_inputs_cached_whitespace_cache_dir.XXXXXX.log")
+inputs_cached_root_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_inputs_cached_root_cache_dir.XXXXXX.log")
 switchkins_checker_unknown_option_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_checker_unknown_option.XXXXXX.log")
 switchkins_checker_too_many_args_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_checker_too_many_args.XXXXXX.log")
 switchkins_cached_missing_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_cached_missing_cache_dir.XXXXXX.log")
 switchkins_cached_whitespace_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_cached_whitespace_cache_dir.XXXXXX.log")
+switchkins_cached_root_cache_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_cached_root_cache_dir.XXXXXX.log")
 switchkins_generator_unknown_option_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_generator_unknown_option.XXXXXX.log")
 switchkins_generator_missing_output_dir_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_generator_missing_output_dir.XXXXXX.log")
 switchkins_generator_too_many_args_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_switchkins_generator_too_many_args.XXXXXX.log")
@@ -99,10 +101,12 @@ cleanup_native_test_temps() {
         "$kinematics_unknown_output_log" \
         "$inputs_cached_missing_cache_dir_log" \
         "$inputs_cached_whitespace_cache_dir_log" \
+        "$inputs_cached_root_cache_dir_log" \
         "$switchkins_checker_unknown_option_log" \
         "$switchkins_checker_too_many_args_log" \
         "$switchkins_cached_missing_cache_dir_log" \
         "$switchkins_cached_whitespace_cache_dir_log" \
+        "$switchkins_cached_root_cache_dir_log" \
         "$switchkins_generator_unknown_option_log" \
         "$switchkins_generator_missing_output_dir_log" \
         "$switchkins_generator_too_many_args_log" \
@@ -254,10 +258,12 @@ for forbidden_manual_cleanup in \
     'rm -f "$kinematics_unknown_output_log"' \
     'rm -f "$inputs_cached_missing_cache_dir_log"' \
     'rm -f "$inputs_cached_whitespace_cache_dir_log"' \
+    'rm -f "$inputs_cached_root_cache_dir_log"' \
     'rm -f "$switchkins_checker_unknown_option_log"' \
     'rm -f "$switchkins_checker_too_many_args_log"' \
     'rm -f "$switchkins_cached_missing_cache_dir_log"' \
     'rm -f "$switchkins_cached_whitespace_cache_dir_log"' \
+    'rm -f "$switchkins_cached_root_cache_dir_log"' \
     'rm -f "$switchkins_generator_unknown_option_log"' \
     'rm -f "$switchkins_generator_missing_output_dir_log"' \
     'rm -f "$switchkins_generator_too_many_args_log"' \
@@ -1408,6 +1414,17 @@ if ! grep -F "CNC_SIM_PREFLIGHT_CACHE_DIR must not contain whitespace: build/inp
     sed -n '1,20p' "$inputs_cached_whitespace_cache_dir_log" >&2
     exit 1
 fi
+if ./check-linuxcnc-inputs-cached.sh --cache-dir / linuxcnc-rs274-source-files.txt \
+    >"$inputs_cached_root_cache_dir_log" 2>&1; then
+    echo "cached LinuxCNC input checker accepted filesystem-root cache dir" >&2
+    exit 1
+fi
+if ! grep -F "CNC_SIM_PREFLIGHT_CACHE_DIR must not be the filesystem root" \
+    "$inputs_cached_root_cache_dir_log" >/dev/null; then
+    echo "cached LinuxCNC input checker did not report filesystem-root cache dirs clearly" >&2
+    sed -n '1,20p' "$inputs_cached_root_cache_dir_log" >&2
+    exit 1
+fi
 if ./check-linuxcnc-switchkins-remap-table-cached.sh --cache-dir >"$switchkins_cached_missing_cache_dir_log" 2>&1; then
     echo "cached switchkins remap table checker accepted --cache-dir without a value" >&2
     exit 1
@@ -1428,6 +1445,17 @@ if ! grep -F "CNC_SIM_PREFLIGHT_CACHE_DIR must not contain whitespace: build/swi
     sed -n '1,20p' "$switchkins_cached_whitespace_cache_dir_log" >&2
     exit 1
 fi
+if ./check-linuxcnc-switchkins-remap-table-cached.sh --cache-dir / \
+    linuxcnc-kinematics-source-files.txt >"$switchkins_cached_root_cache_dir_log" 2>&1; then
+    echo "cached switchkins remap table checker accepted filesystem-root cache dir" >&2
+    exit 1
+fi
+if ! grep -F "CNC_SIM_PREFLIGHT_CACHE_DIR must not be the filesystem root" \
+    "$switchkins_cached_root_cache_dir_log" >/dev/null; then
+    echo "cached switchkins remap table checker did not report filesystem-root cache dirs clearly" >&2
+    sed -n '1,20p' "$switchkins_cached_root_cache_dir_log" >&2
+    exit 1
+fi
 if ./generate-linuxcnc-switchkins-remap-table.sh --unknown >"$switchkins_generator_unknown_option_log" 2>&1; then
     echo "switchkins remap table generator accepted an unknown option" >&2
     exit 1