diff --git a/tests/test_issue42_skill_blocks.py b/tests/test_issue42_skill_blocks.py
index 7989016..0b979cd 100644
--- a/tests/test_issue42_skill_blocks.py
+++ b/tests/test_issue42_skill_blocks.py
@@ -152,6 +152,8 @@ def test_exit_table_agrees_with_script(script):
     raised = _scan_exits(script)[1]
     assert {c: f"{script}:{n}" for c, n in raised.items()} == passthrough, \
         f"{script}: SystemExit codes in heredocs {raised} must be declared as passthrough (and in the table)"
+    assert set(passthrough) <= numeric, \
+        f"{script}: passthrough codes {sorted(set(passthrough) - numeric)} missing from the exit table"
     assert numeric <= literal | set(passthrough), \
         f"table codes {sorted(numeric - literal - set(passthrough))} come from nowhere in {script}"
     for code, ref in passthrough.items():