diff --git a/bytearr.c b/bytearr.c
index 554961f..1e6a93e 100644
--- a/bytearr.c
+++ b/bytearr.c
@@ -776,7 +776,7 @@ static int lbytearr_writestr( lua_State *L )
   const char *pstr = lua_tostring(L, 2);
   uint8_t *str = &getBuffer(p)[getPosition(p)];
   
-  size_t l = 1 + lua_objlen(L, 2);
+  size_t l = 1 + strlen(pstr);
   
   handle_scope_except();