diff --git a/luametalatex-pdf-font-ttf.lua b/luametalatex-pdf-font-ttf.lua
index c72b07c..5a2e837 100644
--- a/luametalatex-pdf-font-ttf.lua
+++ b/luametalatex-pdf-font-ttf.lua
@@ -18,11 +18,11 @@ local function addglyph(glyph, usedcids, cidtogid)
       local flags, component = string.unpack(">I2I2", glyph, offset)
       local gid = cidtogid[component]
       if not gid then
-        gid = #usedcids
-        usedcids[gid+1] = {component}
+        gid = #usedcids+1
+        usedcids[gid] = {component}
         cidtogid[component] = gid
       end
-      glyph = glyph:sub(1, offset+1) .. string.pack(">I2", gid).. glyph:sub(offset+4)
+      glyph = glyph:sub(1, offset+1) .. string.pack(">I2", gid-1).. glyph:sub(offset+4)
       offset = flags&32==32 and offset + 4 + (flags&1==1 and 4 or 2) + (flags&8==8 and 2 or (flags&64==64 and 4 or (flags&128==128 and 8 or 0)))
     end
   end
@@ -69,7 +69,7 @@ local function readpostnames(buf, i, usedcids, encoding)
   return newusedcids
 end
 return function(filename, fontid, reencode)
-  local file <close> = readfile('truetype', filename)
+  local file <close> = assert(readfile('truetype', filename))
   local buf = file()
   local magic, tables = sfnt.parse(buf, 1, fontid)
   if magic ~= "\0\1\0\0" then error[[Invalid TTF font]] end
diff --git a/luametalatex-readfile.lua b/luametalatex-readfile.lua
index 1cf3a2e..380363e 100644
--- a/luametalatex-readfile.lua
+++ b/luametalatex-readfile.lua
@@ -7,17 +7,17 @@ local callbacks = require'luametalatex-callbacks'
 -- local categories = { data = 1, map = 2, image = 3, subset = 4, font = 5 -- , enc = 6, pdf_stream = 7, pdf_stream = 8, silent = 9}
 
 local our_callbacks = {
-  vf       = {'vf',             false, 'rb', 'find_vf_file_callback',       'read_vf_file_callback'},
-  tfm      = {'tfm',            false, 'rb', 'find_font_file_callback',     'read_font_file_callback'},
-  map      = {'map',            2,     'rb', 'find_map_file_callback',      'read_map_file_callback'},
-  enc      = {'enc',            false, 'rb', 'find_enc_file_callback',      'read_enc_file_callback'},
-  type1    = {'type1 fonts',    4,     'rb', 'find_type1_file_callback',    'read_type1_file_callback'},
-  truetype = {'truetype fonts', 4,     'rb', 'find_truetype_file_callback', 'read_truetype_file_callback'},
-  opentype = {'opentype fonts', 4,     'rb', 'find_opentype_file_callback', 'read_opentype_file_callback'},
-  pk       = {'pk',             4,     'rb', 'find_pk_file_callback',       'read_pk_file_callback'},
-  enc      = {'enc files',      false, 'rb', 'find_enc_file_callback',      'read_enc_file_callback'},
-  image    = {'tex',            3,     'rb', 'find_image_file_callback',    'read_image_file_callback'},
-  data     = {'tex',            1,     'rb', 'find_data_file_callback',     'read_data_file_callback'},
+  vf       = {'vf',             false, 'rb', 'find_vf_file',       'read_vf_file'},
+  tfm      = {'tfm',            false, 'rb', 'find_font_file',     'read_font_file'},
+  map      = {'map',            2,     'rb', 'find_map_file',      'read_map_file'},
+  enc      = {'enc',            false, 'rb', 'find_enc_file',      'read_enc_file'},
+  type1    = {'type1 fonts',    4,     'rb', 'find_type1_file',    'read_type1_file'},
+  truetype = {'truetype fonts', 4,     'rb', 'find_truetype_file', 'read_truetype_file'},
+  opentype = {'opentype fonts', 4,     'rb', 'find_opentype_file', 'read_opentype_file'},
+  pk       = {'pk',             4,     'rb', 'find_pk_file',       'read_pk_file'},
+  enc      = {'enc files',      false, 'rb', 'find_enc_file',      'read_enc_file'},
+  image    = {'tex',            3,     'rb', 'find_image_file',    'read_image_file'},
+  data     = {'tex',            1,     'rb', 'find_data_file',     'read_data_file'},
 }
 
 local start_categories = { [0] = '?', '(', '{', '<', '<', '<<' }