diff --git a/list-filtered-existing-paths.sh b/list-filtered-existing-paths.sh
index 38ff536..9590332 100755
--- a/list-filtered-existing-paths.sh
+++ b/list-filtered-existing-paths.sh
@@ -21,6 +21,10 @@ filter=$1
 missing_path_message=$2
 missing_filter_message=$3
 missing_path_hint=${4:-}
+if [[ -n "$filter" && ( "$filter" == */* || "$filter" == "." || "$filter" == ".." ) ]]; then
+    echo "source filter must be a basename: $filter" >&2
+    exit 1
+fi
 
 found=0
 while IFS= read -r path; do
diff --git a/test-all-native.sh b/test-all-native.sh
index a7c7510..d51de34 100755
--- a/test-all-native.sh
+++ b/test-all-native.sh
@@ -29,6 +29,7 @@ missing_api_source_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_rs274_api_proje
 missing_core_source_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_core_source.XXXXXX.log")
 missing_bridge_source_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_bridge_smoke_project_source.XXXXXX.log")
 escaped_project_source_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_escaped_project_source.XXXXXX.log")
+invalid_source_filter_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_invalid_source_filter.XXXXXX.log")
 missing_cmake_set_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_cmake_set.XXXXXX.log")
 missing_cmake_append_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_missing_cmake_append.XXXXXX.log")
 invalid_cmake_set_log=$(mktemp "${TMPDIR:-/tmp}/cnc_sim_invalid_cmake_set.XXXXXX.log")
@@ -63,6 +64,7 @@ cleanup_native_test_temps() {
         "$missing_core_source_log" \
         "$missing_bridge_source_log" \
         "$escaped_project_source_log" \
+        "$invalid_source_filter_log" \
         "$missing_cmake_set_log" \
         "$missing_cmake_append_log" \
         "$invalid_cmake_set_log" \
@@ -182,6 +184,7 @@ for forbidden_manual_cleanup in \
     'rm -f "$missing_core_source_log"' \
     'rm -f "$missing_bridge_source_log"' \
     'rm -f "$escaped_project_source_log"' \
+    'rm -f "$invalid_source_filter_log"' \
     'rm -f "$missing_cmake_set_log"' \
     'rm -f "$missing_cmake_append_log"' \
     'rm -f "$invalid_cmake_set_log"' \
@@ -232,6 +235,7 @@ grep -F 'CMake source relative prefix must stay project-relative: $relative_pref
 grep -F 'missing CMake source set: " set_name' list-cmake-set-sources.sh >/dev/null
 grep -F 'missing CMake append source set: " append_name' list-cmake-set-plus-append-sources.sh >/dev/null
 grep -F 'echo "$missing_path_message: $path"' list-filtered-existing-paths.sh >/dev/null
+grep -F 'source filter must be a basename: $filter' list-filtered-existing-paths.sh >/dev/null
 grep -F 'project source path must stay project-relative: $path' list-filtered-existing-paths.sh >/dev/null
 grep -F "build LinuxCNC first or set LINUXCNC_ROOT to a built tree" list-linuxcnc-source-support-objects.sh >/dev/null
 if ./list-cmake-set-sources.sh does_not_exist_cmake_set >"$missing_cmake_set_log" 2>&1; then
@@ -283,6 +287,18 @@ if ! grep -F "CMake source relative prefix must stay project-relative: ../core/"
     sed -n '1,20p' "$escaped_cmake_prefix_log" >&2
     exit 1
 fi
+if printf 'core/src/canon_event_sink.cpp\n' | ./list-filtered-existing-paths.sh \
+    core/src/canon_event_sink.cpp \
+    "missing project source" \
+    "missing project source in list" >"$invalid_source_filter_log" 2>&1; then
+    echo "source-list filter accepted a path-like filter" >&2
+    exit 1
+fi
+if ! grep -F "source filter must be a basename: core/src/canon_event_sink.cpp" "$invalid_source_filter_log" >/dev/null; then
+    echo "source-list filter did not report path-like filters clearly" >&2
+    sed -n '1,20p' "$invalid_source_filter_log" >&2
+    exit 1
+fi
 if printf '../core/src/canon_event_sink.cpp\n' | ./list-filtered-existing-paths.sh \
     --project-relative \
     "" \