diff --git a/lib/block_io/helper.rb b/lib/block_io/helper.rb
index 4a6a566..7ec5521 100644
--- a/lib/block_io/helper.rb
+++ b/lib/block_io/helper.rb
@@ -253,7 +253,7 @@ def self.decrypt(encrypted_data, b64_enc_key, iv = nil, cipher_type = "AES-256-E
       response = nil
 
       begin
-        aes = OpenSSL::Cipher.new(cipher_type)
+        aes = OpenSSL::Cipher.new(cipher_type.downcase)
         aes.decrypt
         aes.key = b64_enc_key.unpack("m0")[0]
         aes.iv = [iv].pack("H*") unless iv.nil?
@@ -270,7 +270,7 @@ def self.decrypt(encrypted_data, b64_enc_key, iv = nil, cipher_type = "AES-256-E
     
     # Encrypts a block of data given an encryption key
     def self.encrypt(data, b64_enc_key, iv = nil, cipher_type = "AES-256-ECB", auth_data = nil)
-      aes = OpenSSL::Cipher.new(cipher_type)
+      aes = OpenSSL::Cipher.new(cipher_type.downcase)
       aes.encrypt
       aes.key = b64_enc_key.unpack("m0")[0]
       aes.iv = [iv].pack("H*") unless iv.nil?