1 files changed, 2 insertions, 0 deletions
diff --git a/src/lua.js b/src/lua.js
index 4710ded..85d4b64 100644
--- a/src/lua.js
+++ b/src/lua.js
@@ -135,6 +135,8 @@ class lua_Debug {
 }
 
 const to_luastring = function(str, maxBytesToWrite) {
+    assert(typeof str === "string", "to_luastring expect a js string");
+
     maxBytesToWrite = maxBytesToWrite !== undefined ? maxBytesToWrite : Number.MAX_SAFE_INTEGER;
     let outU8Array = [];