diff --git a/autoload/vimtex/complete.vim b/autoload/vimtex/complete.vim
index 7690efc..381e75b 100644
--- a/autoload/vimtex/complete.vim
+++ b/autoload/vimtex/complete.vim
@@ -465,8 +465,12 @@ function! s:labels_parse_number(num_tree) " {{{1
   if len(a:num_tree) == 0
     return '-'
   elseif len(a:num_tree) == 1
-    let l:num = str2nr(a:num_tree[0])
-    return l:num > 0 ? l:num : '-'
+    if type(a:num_tree) == type([])
+      return s:labels_parse_number(a:num_tree[0])
+    else
+      let l:num = str2nr(a:num_tree[0])
+      return l:num > 0 ? l:num : '-'
+    endif
   else
     return s:labels_parse_number(a:num_tree[1])
   endif