diff --git a/run_tests.sh b/run_tests.sh
index 5f4cd5c..92625fb 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -10,6 +10,10 @@ for arg in "$@"; do [[ "$arg" == "--no-gameplay" ]] && SKIP_GAMEPLAY=1; done
 echo "=== gdlint ==="
 gdlint *.gd levels/*.gd tests/*.gd
 
+echo ""
+echo "=== Harness self-test (shared test_helpers: seeded RNG + approx + tally) ==="
+"$GODOT" --headless --script tests/harness_selftest.gd
+
 echo ""
 echo "=== Logic tests ==="
 "$GODOT" --headless --script tests/logic_test.gd