diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9827680..1da320a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
         ruby:
           - 2.6
           - 2.7
-          - 3.0
+          - "3.0"
           - 3.1
           - ruby-head
           - jruby
diff --git a/.github/workflows/generate-docs.yml b/.github/workflows/generate-docs.yml
new file mode 100644
index 0000000..b8d16ed
--- /dev/null
+++ b/.github/workflows/generate-docs.yml
@@ -0,0 +1,27 @@
+name: Build & deploy documentation
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Update gh-pages with docs
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.1"
+      - name: Install required gem dependencies
+        run: gem install yard --no-document
+      - name: Build YARD Ruby Documentation
+        run: yardoc
+      - name: Deploy
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./doc/yard
+          publish_branch: gh-pages
diff --git a/README.md b/README.md
index 8c79112..6cfd5e3 100644
--- a/README.md
+++ b/README.md
@@ -10,8 +10,8 @@
 ## Description
 This is a [Ruby][] implementation of an [EBNF][] and [BNF][] parser and parser generator.
 
-### [PEG][]/[Packrat][] Parser
-In the primary mode, it supports a Parsing Expression Grammar ([PEG][]) parser generator. This performs more minmal transformations on the parsed grammar to extract sub-productions, which allows each component of a rule to generate its own parsing event.
+### [PEG][] / [Packrat][] Parser
+In the primary mode, it supports a Parsing Expression Grammar ([PEG][]) parser generator. This performs more minimal transformations on the parsed grammar to extract sub-productions, which allows each component of a rule to generate its own parsing event.
 
 The resulting {EBNF::PEG::Rule} objects then parse each associated rule according to the operator semantics and use a [Packrat][] memoizer to reduce extra work when backtracking.
 
@@ -77,13 +77,13 @@ Generate formatted grammar using HTML (requires [Haml][Haml] gem):
 
 The EBNF gem can also parse [ISO/EIC 14977] Grammars (ISOEBNF) to [S-Expressions][S-Expression].
 
-    grammar = EBNF.parse(File.open('./etc/iso-ebnf.isoebnf', format: :isoebnf))
+    grammar = EBNF.parse(File.open('./etc/iso-ebnf.isoebnf'), format: :isoebnf)
 
 ### Parsing an ABNF Grammar
 
 The EBNF gem can also parse [ABNF] Grammars to [S-Expressions][S-Expression].
 
-    grammar = EBNF.parse(File.open('./etc/abnf.abnf', format: :abnf))
+    grammar = EBNF.parse(File.open('./etc/abnf.abnf'), format: :abnf)
 
 ### Parser Debugging
 
@@ -278,7 +278,7 @@ A copy of the [Turtle EBNF][] and derived parser files are included in the repos
 [ABNF]:         https://www.rfc-editor.org/rfc/rfc5234
 [BNF]:          https://en.wikipedia.org/wiki/Backus–Naur_form
 [EBNF]:         https://www.w3.org/TR/REC-xml/#sec-notation
-[EBNF doc]:     https://rubydoc.info/github/dryruby/ebnf
+[EBNF doc]:     https://dryruby.github.io/ebnf
 [First/Follow]: https://en.wikipedia.org/wiki/LL_parser#Constructing_an_LL.281.29_parsing_table
 [ISO/IEC 14977]:https://www.iso.org/standard/26153.html
 [LL(1)]:        https://www.csd.uwo.ca/~moreno//CS447/Lectures/Syntax.html/node14.html
diff --git a/VERSION b/VERSION
index 276cbf9..2bf1c1c 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.3.0
+2.3.1
diff --git a/ebnf.gemspec b/ebnf.gemspec
index 36b2306..5b60f1d 100755
--- a/ebnf.gemspec
+++ b/ebnf.gemspec
@@ -10,6 +10,12 @@ Gem::Specification.new do |gem|
   gem.license               = 'Unlicense'
   gem.summary               = "EBNF parser and parser generator in Ruby."
   gem.description           = %q{EBNF is a Ruby parser for W3C EBNF and a parser generator for PEG and LL(1). Also includes parsing modes for ISO EBNF and ABNF.}
+  gem.metadata           = {
+    "documentation_uri" => "https://dryruby.github.io/ebnf",
+    "bug_tracker_uri"   => "https://github.com/dryruby/ebnf/issues",
+    "homepage_uri"      => "https://github.com/dryruby/ebnf",
+    "source_code_uri"   => "https://github.com/dryruby/ebnf",
+  }
 
   gem.authors               = ['Gregg Kellogg']
   gem.email                 = 'public-rdf-ruby@w3.org'
diff --git a/examples/ebnf-peg-parser/README.md b/examples/ebnf-peg-parser/README.md
index a51ccb3..2e3b91a 100644
--- a/examples/ebnf-peg-parser/README.md
+++ b/examples/ebnf-peg-parser/README.md
@@ -158,7 +158,7 @@ The `ebnf` production uses the `alt` operator. When matching the production itse
 [YARD-GS]:      https://rubydoc.info/docs/yard/file/docs/GettingStarted.md
 [PDD]:          https://lists.w3.org/Archives/Public/public-rdf-ruby/2010May/0013.html
 [EBNF]:         https://www.w3.org/TR/REC-xml/#sec-notation
-[EBNF doc]:     https://rubydoc.info/github/dryruby/ebnf/
+[EBNF doc]:     https://dryruby.github.io/ebnf
 [Packrat]:      https://pdos.csail.mit.edu/~baford/packrat/thesis/
 [PEG]:          https://en.wikipedia.org/wiki/Parsing_expression_grammar
 [S-expression]: https://en.wikipedia.org/wiki/S-expression
diff --git a/examples/isoebnf/README.md b/examples/isoebnf/README.md
index 957fb6e..15b97f5 100644
--- a/examples/isoebnf/README.md
+++ b/examples/isoebnf/README.md
@@ -129,7 +129,7 @@ Looking at the grammar itself, we can see that the first declaration is
 [YARD-GS]:      https://rubydoc.info/docs/yard/file/docs/GettingStarted.md
 [PDD]:          https://lists.w3.org/Archives/Public/public-rdf-ruby/2010May/0013.html
 [EBNF]:         https://www.w3.org/TR/REC-xml/#sec-notation
-[EBNF doc]:     https://rubydoc.info/github/dryruby/ebnf/
+[EBNF doc]:     https://dryruby.github.io/ebnf
 [Packrat]:      https://pdos.csail.mit.edu/~baford/packrat/thesis/
 [PEG]:          https://en.wikipedia.org/wiki/Parsing_expression_grammar
 [ISO/IEC 14977]:https://www.iso.org/standard/26153.html
diff --git a/lib/ebnf/rule.rb b/lib/ebnf/rule.rb
index 39625e6..37fb189 100644
--- a/lib/ebnf/rule.rb
+++ b/lib/ebnf/rule.rb
@@ -367,11 +367,11 @@ def to_peg
     def to_regexp
       case expr.first
       when :hex
-        Regexp.new(translate_codepoints(expr[1]))
+        Regexp.new(Regexp.escape(translate_codepoints(expr[1])))
       when :istr
         /#{expr.last}/ui
       when :range
-        Regexp.new("[#{translate_codepoints(expr[1])}]")
+        Regexp.new("[#{escape_regexp_character_range(translate_codepoints(expr[1]))}]")
       else
         raise "Can't turn #{expr.inspect} into a regexp"
       end
@@ -770,5 +770,11 @@ def make_sym_id(variation = nil)
       @id_seq += 1
       ["_#{@sym}_#{@id_seq}#{variation}".to_sym, ("#{@id}.#{@id_seq}#{variation}" if @id)]
     end
+
+    # Escape "[", "]", and "\" in ranges so they don't result in a warning or error
+    # about empty character classes.
+    def escape_regexp_character_range(character_range)
+      character_range.gsub(/([\[\]\\])/) {|char| "\\#{char}"}
+    end
   end
-end
\ No newline at end of file
+end
diff --git a/spec/rule_spec.rb b/spec/rule_spec.rb
index bffb777..a11f56a 100644
--- a/spec/rule_spec.rb
+++ b/spec/rule_spec.rb
@@ -481,9 +481,13 @@
   describe "#to_regexp" do
     {
       hex: [:hex, "#x20", / /],
+      hex: [:hex, "#x5c", /\\/],
       range: [:range, "a-b", /[a-b]/],
       range2: [:range, "a-zA-Z", /[a-zA-Z]/],
       range3: [:range, "abc-", /[abc-]/],
+      range4: [:range, "#x23-#x5b", /[#-\[]/],
+      range5: [:range, "#x5d-#x5e", /[\]-^]/],
+      range6: [:range, "#x5c-#x5e", /[\\-^]/],
     }.each do |title, (op, exp, regexp)|
       it title do
         expect(EBNF::Rule.new(title, nil, [op, exp]).to_regexp).to eql regexp
@@ -1055,4 +1059,4 @@
       end
     end
   end
-end
\ No newline at end of file
+end