diff --git a/ruby/Gemfile b/ruby/Gemfile
index 1d2f6b5..b969649 100644
--- a/ruby/Gemfile
+++ b/ruby/Gemfile
@@ -7,4 +7,3 @@ gem "parser", "~> 3.3.10"
 gem "rake", "~> 13.0"
 gem "reline", "~> 0.6"
 gem "standard", "~> 1.52.0", require: false
-gem "wordexp", "~> 0.2"
diff --git a/ruby/Gemfile.lock b/ruby/Gemfile.lock
index 2dfefe6..88cc954 100644
--- a/ruby/Gemfile.lock
+++ b/ruby/Gemfile.lock
@@ -92,7 +92,6 @@ GEM
     unicode-display_width (3.2.0)
       unicode-emoji (~> 4.1)
     unicode-emoji (4.2.0)
-    wordexp (0.2.2)
 
 PLATFORMS
   arm64-darwin-21
@@ -103,13 +102,12 @@ PLATFORMS
 
 DEPENDENCIES
   guard (~> 2.19)
-  guard-rake
+  guard-rake (~> 1.0)
   minitest (~> 6.0)
   parser (~> 3.3.10)
   rake (~> 13.0)
   reline (~> 0.6)
   standard (~> 1.52.0)
-  wordexp (~> 0.2)
 
 BUNDLED WITH
   4.0.3
diff --git a/ruby/shell/repl.rb b/ruby/shell/repl.rb
index 1136ec3..94bf78c 100644
--- a/ruby/shell/repl.rb
+++ b/ruby/shell/repl.rb
@@ -3,30 +3,32 @@ begin
 rescue LoadError
   require "reline"
 end
-require "wordexp"
 
 require "shell/builtins"
 require "shell/colours"
 require "shell/job_control"
 require "shell/logger"
+require "shell/word_expander"
 
 module Shell
   class REPL
     include Colours
 
-    attr_reader :builtins, :job_control, :logger, :options
+    attr_reader :builtins, :job_control, :logger, :options, :word_expander
 
     attr_accessor :precmd_hook
 
-    def initialize(builtins: nil, job_control: nil, logger: nil)
+    def initialize(builtins: nil, job_control: nil, logger: nil, word_expander: nil)
       logger ||= Logger.instance
       job_control ||= JobControl.new(logger: logger)
       builtins ||= Builtins.new(job_control: job_control)
+      word_expander ||= WordExpander.new
 
       @builtins = builtins
       @job_control = job_control
       @logger = logger
       @options = {}
+      @word_expander = word_expander
     end
 
     def start(options: nil)
@@ -48,7 +50,7 @@ module Shell
       return 0 if line.strip.empty? # no input, no-op
 
       logger.verbose "Processing command: #{line.inspect}"
-      args = Wordexp.expand(line)
+      args = word_expander.expand(line)
       cmd = args.shift
       logger.verbose "Parsed command: #{cmd} #{args.inspect}"
       if builtins.builtin?(cmd)
diff --git a/ruby/shell/word_expander.rb b/ruby/shell/word_expander.rb
new file mode 100644
index 0000000..aaf30a3
--- /dev/null
+++ b/ruby/shell/word_expander.rb
@@ -0,0 +1,93 @@
+require "shellwords"
+
+module Shell
+  class WordExpander
+    ENV_VAR_REGEX = /\$(?:\{([^}]+)\}|(\w+)\b)/
+
+    # Splits the given line into multiple words, performing the following transformations:
+    #
+    # - Splits into words taking quoting and backslash escaping into account
+    # - Expands environment variables using $NAME and ${NAME} syntax
+    # - Tilde expansion, which means that ~ is expanded to $HOME
+    # - Glob expansion on files and directories
+    def expand(line)
+      shellsplit(line)
+        .map do |word|
+          word
+            .gsub(ENV_VAR_REGEX) do
+              name = Regexp.last_match(2) || Regexp.last_match(1)
+              ENV.fetch(name)
+            end
+          # TODO: expand globs
+        end
+    end
+
+    # Lifted directly from Ruby 4.0.0.
+    #
+    # Splits a string into an array of tokens in the same way the UNIX
+    # Bourne shell does.
+    #
+    #   argv = Shellwords.split('here are "two words"')
+    #   argv #=> ["here", "are", "two words"]
+    #
+    # +line+ must not contain NUL characters because of nature of
+    # +exec+ system call.
+    #
+    # Note, however, that this is not a command line parser.  Shell
+    # metacharacters except for the single and double quotes and
+    # backslash are not treated as such.
+    #
+    #   argv = Shellwords.split('ruby my_prog.rb | less')
+    #   argv #=> ["ruby", "my_prog.rb", "|", "less"]
+    #
+    # String#shellsplit is a shortcut for this function.
+    #
+    #   argv = 'here are "two words"'.shellsplit
+    #   argv #=> ["here", "are", "two words"]
+    def shellsplit(line)
+      words = []
+      field = "".dup
+      at_word_start = true
+      found_glob_char = false
+      line.scan(/\G\s*(?>([^\0\s\\'"]+)|'([^\0']*)'|"((?:[^\0"\\]|\\[^\0])*)"|(\\[^\0]?)|(\S))(\s|\z)?/m) do
+        |word, sq, dq, esc, garbage, sep|
+        if garbage
+          b = $~.begin(0)
+          line = $~[0]
+          line = "..." + line if b > 0
+          raise ArgumentError, "#{(garbage == "\0") ? "Nul character" : "Unmatched quote"} at #{b}: #{line}"
+        end
+        # 2.2.3 Double-Quotes:
+        #
+        #   The <backslash> shall retain its special meaning as an
+        #   escape character only when followed by one of the following
+        #   characters when considered special:
+        #
+        #   $ ` " \ <newline>
+        field << (word || sq || (dq && dq.gsub(/\\([$`"\\\n])/, '\\1')) || esc.gsub(/\\(.)/, '\\1'))
+        found_glob_char = word && word =~ /[*?\[]/ # must be unquoted
+        # Expand tildes at the beginning of unquoted words.
+        if word && at_word_start
+          field.sub!(/^~/, Dir.home)
+        end
+        at_word_start = false
+        if sep
+          if found_glob_char
+            glob_words = expand_globs(field)
+            words += (glob_words.empty? ? [field] : glob_words)
+          else
+            words << field
+          end
+          field = "".dup
+          at_word_start = true
+          found_glob_char = false
+        end
+      end
+      words
+    end
+
+    def expand_globs(word)
+      Dir.glob(word)
+    end
+  end
+end
diff --git a/ruby/test/shell_test.rb b/ruby/test/shell_test.rb
index 4256b37..59daea6 100644
--- a/ruby/test/shell_test.rb
+++ b/ruby/test/shell_test.rb
@@ -19,7 +19,8 @@ class ShellTest < Minitest::Test
 
   def test_expands_environment_variables
     assert_equal Dir.home, `#{A1_PATH} -c 'echo $HOME'`.chomp
-    assert system("#{A1_PATH} -c 'echo $HOME' >/dev/null")
+    assert_equal Dir.home, `#{A1_PATH} -c 'echo ${HOME}'`.chomp
+    assert_equal "#{Dir.home} #{Dir.home}", `#{A1_PATH} -c 'echo ${HOME} ${HOME}'`.chomp
   end
 
   def test_fails_on_unknown_variables