diff --git a/luamml-patches-kernel.sty b/luamml-patches-kernel.sty
index e150a33..e03a991 100644
--- a/luamml-patches-kernel.sty
+++ b/luamml-patches-kernel.sty
@@ -33,3 +33,27 @@
   \int_gincr:N \g__luamml_kernel_phantom_int
   \__luamml_kernel_phantom:Vnn \g__luamml_kernel_phantom_int
 }
+
+\@ifpackageloaded {unicode-math} {} {
+  \cs_new:Npn \__luamml_kernel_define_character:Nnn #1#2#3 {
+    \cs_set:cpx { \cs_to_str:N #1 ~ } {
+      \luamml_annotate:nen {#2} {
+        nucleus = true, core = {[0] = 'mi', '\string\u{#3}'},
+      } {
+        \exp_not:v { \cs_to_str:N #1 ~ }
+      }
+    }
+  }
+
+  \__luamml_kernel_define_character:Nnn \models {3} {22a7}
+  \__luamml_kernel_define_character:Nnn \hookrightarrow {3} {21aa}
+  \__luamml_kernel_define_character:Nnn \hookleftarrow {3} {21a9}
+  \__luamml_kernel_define_character:Nnn \bowtie {3} {22c8}
+  \__luamml_kernel_define_character:Nnn \Longrightarrow {3} {27f9}
+  \__luamml_kernel_define_character:Nnn \longrightarrow {3} {27f6}
+  \__luamml_kernel_define_character:Nnn \Longleftarrow {3} {27f8}
+  \__luamml_kernel_define_character:Nnn \longleftarrow {3} {27f5}
+  \__luamml_kernel_define_character:Nnn \Longleftrightarrow {3} {27fa}
+  \__luamml_kernel_define_character:Nnn \longleftrightarrow {3} {27f7}
+  \__luamml_kernel_define_character:Nnn \longmapsto {4} {27fc}
+}
diff --git a/pdfmml-showlists.lua b/pdfmml-showlists.lua
index 8d0a9dc..340c9f9 100644
--- a/pdfmml-showlists.lua
+++ b/pdfmml-showlists.lua
@@ -130,8 +130,15 @@ function parse_list(lines, i, prefix, parsed)
           local mark = mark_whatsit:match(line, #prefix+1)
           if mark then
             local mark_table = assert(load('return {' .. assert(parsed.marks[mark], 'Undefined mark encountered') .. '}', nil, 't', mark_environment))()
-            current_mark, current_count = mark_table, mark_table.count or 1
-            current_offset = mark_table.offset or current_count
+            if current_mark then
+              if (mark_table.count or 1) > current_count then
+                error'Invalid mark nesting'
+              end
+              -- Ignore new mark if existing mark is evaluated. This should be replaced with proper nesting
+            else
+              current_mark, current_count = mark_table, mark_table.count or 1
+              current_offset = mark_table.offset or current_count
+            end
             i = i + 1
           else
             print(line, prefix, i)