diff --git a/lib/lua/runtime.sx b/lib/lua/runtime.sx
index 28f0b23f..118f9071 100644
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -1215,19 +1215,27 @@
 (define lua-math-pi 3.141592653589793)
 (define lua-math-huge (/ 1.0 0.0))
 
-(define lua-math-abs (fn (x) (abs x)))
-(define lua-math-ceil (fn (x) (ceil x)))
-(define lua-math-floor (fn (x) (floor x)))
-(define lua-math-sqrt (fn (x) (sqrt x)))
-(define lua-math-exp (fn (x) (exp x)))
-(define lua-math-sin (fn (x) (sin x)))
-(define lua-math-cos (fn (x) (cos x)))
-(define lua-math-tan (fn (x) (tan x)))
-(define lua-math-asin (fn (x) (asin x)))
-(define lua-math-acos (fn (x) (acos x)))
-(define lua-math-atan (fn (x) (atan x)))
-(define lua-math-atan2 (fn (y x) (atan2 y x)))
-(define lua-math-pow (fn (a b) (pow a b)))
+(define
+  lua-math-num
+  (fn (name x)
+    (let ((n (lua-to-number x)))
+      (cond
+        ((= n nil) (error (str "bad argument to '" name "' (number expected)")))
+        (else n)))))
+
+(define lua-math-abs (fn (x) (abs (lua-math-num "abs" x))))
+(define lua-math-ceil (fn (x) (ceil (lua-math-num "ceil" x))))
+(define lua-math-floor (fn (x) (floor (lua-math-num "floor" x))))
+(define lua-math-sqrt (fn (x) (sqrt (lua-math-num "sqrt" x))))
+(define lua-math-exp (fn (x) (exp (lua-math-num "exp" x))))
+(define lua-math-sin (fn (x) (sin (lua-math-num "sin" x))))
+(define lua-math-cos (fn (x) (cos (lua-math-num "cos" x))))
+(define lua-math-tan (fn (x) (tan (lua-math-num "tan" x))))
+(define lua-math-asin (fn (x) (asin (lua-math-num "asin" x))))
+(define lua-math-acos (fn (x) (acos (lua-math-num "acos" x))))
+(define lua-math-atan (fn (x) (atan (lua-math-num "atan" x))))
+(define lua-math-atan2 (fn (y x) (atan2 (lua-math-num "atan2" y) (lua-math-num "atan2" x))))
+(define lua-math-pow (fn (a b) (pow (lua-math-num "pow" a) (lua-math-num "pow" b))))
 
 (define lua-math-log
   (fn (&rest args)
diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index 8a4dae70..6e6f18b6 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "totals": {
     "pass": 1,
-    "fail": 8,
-    "timeout": 7,
+    "fail": 12,
+    "timeout": 3,
     "skip": 8,
     "total": 24,
     "runnable": 16,
@@ -10,12 +10,12 @@
   },
   "top_failure_modes": [
     [
-      "timeout",
+      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
       7
     ],
     [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      4
+      "timeout",
+      3
     ],
     [
       "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
@@ -28,6 +28,10 @@
     [
       "undefined symbol: fat\\",
       1
+    ],
+    [
+      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
+      1
     ]
   ],
   "results": [
@@ -47,7 +51,7 @@
       "name": "attrib.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: module 'C' not found\\\\\\\"\\",
-      "ms": 6895
+      "ms": 6525
     },
     {
       "name": "big.lua",
@@ -59,7 +63,7 @@
       "name": "calls.lua",
       "status": "fail",
       "reason": "undefined symbol: fat\\",
-      "ms": 5736
+      "ms": 5092
     },
     {
       "name": "checktable.lua",
@@ -71,7 +75,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8007
+      "ms": 8006
     },
     {
       "name": "code.lua",
@@ -81,9 +85,9 @@
     },
     {
       "name": "constructs.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8008
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
+      "ms": 6780
     },
     {
       "name": "db.lua",
@@ -95,13 +99,13 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3826
+      "ms": 3208
     },
     {
       "name": "events.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8007
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
+      "ms": 7307
     },
     {
       "name": "files.lua",
@@ -119,13 +123,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2748
+      "ms": 1816
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 2339
+      "ms": 1627
     },
     {
       "name": "main.lua",
@@ -137,43 +141,43 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 6042
+      "ms": 4156
     },
     {
       "name": "nextvar.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8007
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
+      "ms": 7064
     },
     {
       "name": "pm.lua",
-      "status": "timeout",
-      "reason": "per-test timeout",
-      "ms": 8010
+      "status": "fail",
+      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
+      "ms": 5813
     },
     {
       "name": "sort.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8007
+      "ms": 8008
     },
     {
       "name": "strings.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6167
+      "ms": 3987
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3432
+      "ms": 2243
     },
     {
       "name": "verybig.lua",
       "status": "pass",
       "reason": "",
-      "ms": 1659
+      "ms": 1085
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 5dab9f84..30be0498 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -1,15 +1,16 @@
 # Lua-on-SX conformance scoreboard
 
 **Pass rate:** 1/16 runnable (6.2%)
-fail=8 timeout=7 skip=8 total=24
+fail=12 timeout=3 skip=8 total=24
 
 ## Top failure modes
 
-- **7x** timeout
-- **4x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
+- **7x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
+- **3x** timeout
 - **2x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio
 - **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\
 - **1x** undefined symbol: fat\
+- **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat
 
 ## Per-test results
 
@@ -17,25 +18,25 @@ fail=8 timeout=7 skip=8 total=24
 |---|---|---|---:|
 | all.lua | skip | driver uses dofile to chain other tests | 0 |
 | api.lua | skip | requires testC (C debug library) | 0 |
-| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6895 |
+| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6525 |
 | big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | undefined symbol: fat\ | 5736 |
+| calls.lua | fail | undefined symbol: fat\ | 5092 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8007 |
+| closure.lua | timeout | per-test timeout | 8006 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
-| constructs.lua | timeout | per-test timeout | 8008 |
+| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat | 6780 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3826 |
-| events.lua | timeout | per-test timeout | 8007 |
+| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3208 |
+| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7307 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2748 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 2339 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 1816 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1627 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 6042 |
-| nextvar.lua | timeout | per-test timeout | 8007 |
-| pm.lua | timeout | per-test timeout | 8010 |
-| sort.lua | timeout | per-test timeout | 8007 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6167 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3432 |
-| verybig.lua | pass | - | 1659 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 4156 |
+| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7064 |
+| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 5813 |
+| sort.lua | timeout | per-test timeout | 8008 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3987 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2243 |
+| verybig.lua | pass | - | 1085 |
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 6f76ba17..45fb945a 100644
--- a/plans/lua-on-sx.md
+++ b/plans/lua-on-sx.md
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25: lua: scoreboard iteration — math fns now error on bad/missing args (was silently returning 0). New `lua-math-num "name" x` validator wraps `abs`/`ceil`/`floor`/`sqrt`/`exp`/`sin`/`cos`/`tan`/`asin`/`acos`/`atan`/`atan2`/`pow`. errors.lua moves past assert #4 (`pcall(math.sin)` now returns false+err as expected).
 - 2026-04-24: lua: scoreboard iteration — **pattern character sets** `[...]` and `[^...]`. New `lua-pat-set-end`/`lua-pat-set-match` helpers handle ranges (`[a-z]`), classes inside sets (`[%d%a]`), negation (`[^abc]`), and `[]...]`/`[^]...]` (literal `]` as first char). Asserts 6→4, but timeouts 3→7 — many tests now reach loop-heavy code. 387/387 green (+3 charset tests).
 - 2026-04-24: lua: scoreboard iteration — `tonumber(s, base)` for bases 2-36. Validates digit ranges per base, supports leading `+`/`-`, trims whitespace. `math.lua` past assert #21. Asserts 8→6, timeouts 3→4. 384/384 green.
 - 2026-04-24: lua: scoreboard iteration — added `lua-unwrap-final-return` (post-processor that rewrites top-level `(raise (list 'lua-ret V))` → `V` so top-level defines leak to SX top and loadstring closures can see them). Tried dropping the function-guard at top level, but too many tests use `if x then return 0 else return err end` at chunk tail, whose returns aren't at the *statement-list* tail — guard still needed. Kept guard + unwrap-as-no-op. Scoreboard unchanged.