diff --git a/vendor/bitn.lua b/vendor/bitn.lua
index 92c9cbe..38c8ed1 100644
--- a/vendor/bitn.lua
+++ b/vendor/bitn.lua
@@ -36,10 +36,18 @@ local MASK32 = 0xFFFFFFFF
 -- Implementation 1: Native operators (Lua 5.3+)
 --------------------------------------------------------------------------------
 
+-- Parsing `a & b` does not mean the result has 64-bit integer semantics. LuaJIT
+-- rolling releases from 2026 accept the syntax and return a signed 32-bit number,
+-- as from its `bit` library, while this branch assumes 5.3+ integers and skips the
+-- to_unsigned() normalisation such a host needs.
+--
+-- So test the value, not the runtime: 5.3+ answers 0xFFFFFFFF and anything with
+-- 32-bit semantics answers -1. Asking the question this way needs no list of which
+-- runtimes exist, so it stays correct for whatever grows the syntax next.
 local ok, result = pcall(load, "return function(a,b) return a & b end")
 if ok and result then
   local fn = result()
-  if fn then
+  if fn and fn(0xFFFFFFFF, 0xFFFFFFFF) == 0xFFFFFFFF then
     -- Native operators available - define all functions using them
     local native_band = fn
     local native_bor = assert(load("return function(a,b) return a | b end"))()
@@ -138,10 +146,12 @@ end
 local bit_lib
 local is_luajit = false
 
--- Try LuaJIT's bit library first
-ok, result = pcall(require, "bit")
-if ok and result then
-  bit_lib = result
+-- Try LuaJIT's bit library first. Fresh locals rather than the pcall results
+-- from the native-operator probe above: that `result` is a compiled chunk, this
+-- one is a library table.
+local bit_ok, bit_module = pcall(require, "bit")
+if bit_ok and bit_module then
+  bit_lib = bit_module
   is_luajit = true
 else
   -- Try Lua 5.2's bit32 library (use rawget to avoid recursion with our module name)
@@ -2646,20 +2656,23 @@ function bit64.selftest()
   for _, test in ipairs(test_vectors) do
     total = total + 1
     local result = test.fn(unpack_fn(test.inputs))
+    -- Held in a local so the type narrowing below applies to it; a table field
+    -- is not narrowed by a `type()` check.
+    local expected = test.expected
 
-    if type(test.expected) == "table" then
+    if type(expected) == "table" then
       -- 64-bit comparison
-      if eq64(result, test.expected) then
+      if eq64(result, expected) then
         print("  PASS: " .. test.name)
         passed = passed + 1
       else
         print("  FAIL: " .. test.name)
-        print("    Expected: " .. fmt64(test.expected))
+        print("    Expected: " .. fmt64(expected))
         print("    Got:      " .. fmt64(result))
       end
-    elseif type(test.expected) == "string" then
+    elseif type(expected) == "string" then
       -- Byte string comparison
-      if result == test.expected then
+      if result == expected then
         print("  PASS: " .. test.name)
         passed = passed + 1
       else
@@ -2669,8 +2682,8 @@ function bit64.selftest()
           print("    Got:      " .. type(result))
         else
           local exp_hex, got_hex = "", ""
-          for i = 1, #test.expected do
-            exp_hex = exp_hex .. string.format("%02X", string.byte(test.expected, i))
+          for i = 1, #expected do
+            exp_hex = exp_hex .. string.format("%02X", string.byte(expected, i))
           end
           for i = 1, #result do
             got_hex = got_hex .. string.format("%02X", string.byte(result, i))
@@ -2680,12 +2693,12 @@ function bit64.selftest()
         end
       end
     else
-      if result == test.expected then
+      if result == expected then
         print("  PASS: " .. test.name)
         passed = passed + 1
       else
         print("  FAIL: " .. test.name)
-        print("    Expected: " .. tostring(test.expected))
+        print("    Expected: " .. tostring(expected))
         print("    Got:      " .. tostring(result))
       end
     end
@@ -3279,7 +3292,7 @@ local bitn = {
 }
 
 --- Library version (injected at build time for releases).
-local VERSION = "v0.6.0"
+local VERSION = "v0.6.1"
 
 --- Get the library version string.
 --- @return string version Version string (e.g., "v1.0.0" or "dev")