diff --git a/luamml-amsmath.lua b/luamml-amsmath.lua
index b8ac0e3..6ee40e0 100644
--- a/luamml-amsmath.lua
+++ b/luamml-amsmath.lua
@@ -43,7 +43,7 @@ token.set_lua('__luamml_amsmath_save_tag:', funcid, 'protected')
 lua.get_functions_table()[funcid] = function()
   local nest = tex.nest.top
   local chars = {}
-  last_tag = to_text(nest.head)
+  last_tag = {[0] = 'mtext', to_text(nest.head)}
 end
 
 funcid = luatexbase.new_luafunction'__luamml_amsmath_set_tag:'
@@ -53,6 +53,6 @@ lua.get_functions_table()[funcid] = function()
     texio.write_nl'WARNING: Tag extraction failed'
     return
   end
-  store_tag({[0] = 'mtd', {[0] = 'mtext', last_tag}})
+  store_tag({[0] = 'mtd', last_tag})
   last_tag = nil
 end
diff --git a/luamml-convert.lua b/luamml-convert.lua
index 58fc4f8..164b733 100644
--- a/luamml-convert.lua
+++ b/luamml-convert.lua
@@ -1,6 +1,6 @@
 local remap_comb = require'luamml-data-combining'
 local stretchy = require'luamml-data-stretchy'
-local to_string = require'luamml-lr'
+local to_text = require'luamml-lr'
 
 local properties = node.get_properties_table()
 
@@ -89,11 +89,8 @@ local function kernel_to_table(kernel, cur_style)
     return result, result
   elseif id == sub_box_t then
     if kernel.list.id == hlist_t then -- We directly give up for vlists
-      local str = to_string(kernel.list.head)
-      if str then
-        local result = {[0] = 'mtext', str}
-        return result, result
-      end
+      local result = {[0] = 'mtext', to_text(kernel.list.head)}
+      return result, result
     else
       local result = {[0] = 'mi', {[0] = 'mglyph', ['tex:box'] = kernel.list}}
       return result, result