diff --git a/lib/i18n.rb b/lib/i18n.rb
index 61132e8b..24bef854 100755
--- a/lib/i18n.rb
+++ b/lib/i18n.rb
@@ -6,15 +6,9 @@
 # Copyright:: Copyright (c) 2008 The Ruby i18n Team
 # License::   MIT
 require 'i18n/backend/simple'
+require 'i18n/exceptions'
 
-module I18n
-  class ArgumentError < ::ArgumentError; end
-  class InvalidLocale < ArgumentError; end
-  class MissingTranslationData < ArgumentError; end
-  class InvalidPluralizationData < ArgumentError; end
-  class MissingInterpolationArgument < ArgumentError; end
-  class ReservedInterpolationKey < ArgumentError; end
-  
+module I18n  
   @@backend = Backend::Simple
   @@default_locale = 'en-US'
   @@exception_handler = :default_exception_handler
diff --git a/lib/i18n/backend/simple.rb b/lib/i18n/backend/simple.rb
index 4f9373e2..baf7fe3f 100644
--- a/lib/i18n/backend/simple.rb
+++ b/lib/i18n/backend/simple.rb
@@ -22,7 +22,7 @@ def store_translations(locale, data)
         end
         
         def translate(key, locale, options = {})
-          raise InvalidLocale, 'locale is nil in I18n::Backend::Simple#translate' if locale.nil?
+          raise InvalidLocale.new(locale) if locale.nil?
           return key.map{|key| translate key, locale, options } if key.is_a? Array
 
           reserved = :scope, :default
@@ -30,7 +30,7 @@ def translate(key, locale, options = {})
           options.delete(:default)
           values = options.reject{|name, value| reserved.include? name } 
 
-          entry = lookup(locale, key, scope) || default(locale, default, options) || raise(I18n::MissingTranslationData, "translation data missing for #{I18n.send(:normalize_translation_keys, locale, key, scope).inspect}")
+          entry = lookup(locale, key, scope) || default(locale, default, options) || raise(I18n::MissingTranslationData.new(key, locale, options))
           entry = pluralize entry, count
           entry = interpolate entry, values
           entry
@@ -94,7 +94,7 @@ def default(locale, default, options = {})
           # implement more flexible or complex pluralization rules.
           def pluralize(entry, count)
             return entry unless entry.is_a?(Array) and count
-            raise InvalidPluralizationData, "translation data #{entry} can not be used with :count => #{count}" unless entry.size == 2
+            raise InvalidPluralizationData.new(entry, count) unless entry.size == 2
             entry[count == 1 ? 0 : 1]
           end
     
@@ -119,8 +119,8 @@ def interpolate(string, values = {})
               key = s.scan_until(/\}\}/)[0..-3]
               end_pos = s.pos - 1            
 
-              raise ReservedInterpolationKey, %s(reserved key :#{key} used in "#{string}") if %w(scope default).include?(key)
-              raise MissingInterpolationArgument, %s(interpolation argument #{key} missing in "#{string}") unless values.has_key? key.to_sym
+              raise ReservedInterpolationKey.new(key, string) if %w(scope default).include?(key)
+              raise MissingInterpolationArgument.new(key, string) unless values.has_key? key.to_sym
 
               s.string[start_pos..end_pos] = values[key.to_sym].to_s
               s.unscan
diff --git a/lib/i18n/exceptions.rb b/lib/i18n/exceptions.rb
new file mode 100644
index 00000000..3e4ce85e
--- /dev/null
+++ b/lib/i18n/exceptions.rb
@@ -0,0 +1,43 @@
+module I18n
+  class ArgumentError < ::ArgumentError; end
+  class InvalidLocale < ArgumentError
+    attr_reader :locale
+    def initialize(locale)
+      @locale = locale
+      super "#{locale.inspect} is not a valid locale"
+    end
+  end
+
+  class MissingTranslationData < ArgumentError
+    attr_reader :key, :locale, :options
+    def initialize(key, locale, options)
+      @key, @locale, @options = key, locale, options
+      keys = I18n.send(:normalize_translation_keys, locale, key, options[:scope])
+      super "translation data missing for #{keys.inspect}"
+    end
+  end
+
+  class InvalidPluralizationData < ArgumentError
+    attr_reader :entry, :count
+    def initialize(entry, count)
+      @entry, @count = entry, count
+      super "translation data #{entry.inspect} can not be used with :count => #{count}"
+    end
+  end
+
+  class MissingInterpolationArgument < ArgumentError
+    attr_reader :key, :string
+    def initialize(key, string)
+      @key, @string = key, string
+      super %s(interpolation argument #{key} missing in "#{string}")
+    end
+  end
+
+  class ReservedInterpolationKey < ArgumentError
+    attr_reader :key, :string
+    def initialize(key, string)
+      @key, @string = key, string
+      super "reserved key #{key.inspect} used in #{string.inspect}"
+    end
+  end
+end  
\ No newline at end of file