diff --git a/README.md b/README.md
index 3294ad5..2aef3fb 100644
--- a/README.md
+++ b/README.md
@@ -16,8 +16,14 @@ Randomstring.generate
 
 Randomstring.generate(7)
 # >> "xqm5wXX"
+
+Randomstring.generate_alphanumeric_lower
+# >> "4vhp56ijj5lwfd73df1mw07b9llfw783"
+
+Randomstring.generate_custom(8, ['A'..'C'])
+# >> "BBABAAAB"
 ```
 
 ## LICENSE
 
-ruby-randomstring is licensed under the MIT license.
\ No newline at end of file
+ruby-randomstring is licensed under the MIT license.
diff --git a/lib/randomstring.rb b/lib/randomstring.rb
index c6a0496..3d0a674 100644
--- a/lib/randomstring.rb
+++ b/lib/randomstring.rb
@@ -1,8 +1,16 @@
 class Randomstring
+  def self.generate_custom(length = 32, range)
+    characters = range.map{ |i| i.to_a }.flatten
+    (0...length).map{ characters[rand(characters.length)] }.join
+  end
+  
   def self.generate(length = 32)
-    characters = [('0'..'9'), ('a'..'z'), ('A'..'Z')]
-    characters = characters.map{ |i| i.to_a }.flatten
-    string     = (0...length).map{ characters[rand(characters.length)] }.join
-    string
+    range = [('0'..'9'), ('a'..'z'), ('A'..'Z')]
+    generate_custom(length, range)
+  end
+  
+  def self.generate_alphanumeric_lower(length = 32)
+    range = [('0'..'9'), ('a'..'z')]
+    generate_custom(length, range)
   end
-end
\ No newline at end of file
+end