diff --git a/lib/imbecile.rb b/lib/imbecile.rb
index 08dba08..5ada8a3 100644
--- a/lib/imbecile.rb
+++ b/lib/imbecile.rb
@@ -1,7 +1,7 @@
 require_relative "imbecile/cli"
 require_relative "imbecile/grammar"
 require_relative "imbecile/regex"
-require_relative "imbecile/regex/unit"
+require_relative "imbecile/regex/parser"
 require_relative "imbecile/version"
 require "erb"
 
diff --git a/lib/imbecile/regex/unit.rb b/lib/imbecile/regex/parser.rb
similarity index 97%
rename from lib/imbecile/regex/unit.rb
rename to lib/imbecile/regex/parser.rb
index 9dce5c6..8639f44 100644
--- a/lib/imbecile/regex/unit.rb
+++ b/lib/imbecile/regex/parser.rb
@@ -1,7 +1,10 @@
 module Imbecile
   class Regex
 
-    class Unit
+    class Parser
+
+      class Unit
+      end
 
       class SequenceUnit < Unit
         attr_accessor :units
@@ -66,11 +69,13 @@ module Imbecile
         end
       end
 
+      attr_reader :unit
+
       def initialize(pattern)
         @pattern = pattern.dup
         @unit = parse_alternates
         if @pattern != ""
-          raise "Invalid pattern: #{@pattern}"
+          raise Error.new(%[Unexpected "#{@pattern}" in pattern])
         end
       end