diff --git a/lib/letter_avatar/colors.rb b/lib/letter_avatar/colors.rb
index 348c428..0d61e17 100644
--- a/lib/letter_avatar/colors.rb
+++ b/lib/letter_avatar/colors.rb
@@ -276,8 +276,19 @@ module LetterAvatar
 
 		def self.with_custom(username)
 			custom_palette = LetterAvatar.custom_palette
+			raise "Missing Custom Palette, please set config.custom_palette if using :custom" if custom_palette.nil?
+			raise "Invalid Custom Palette, please update config.custom_palette" unless valid_custom_palette
 			custom_palette[Digest::MD5.hexdigest(username)[0...15].to_i(16) % custom_palette.length]
 		end
+		
+		def self.valid_custom_palette
+			palette = LetterAvatar.custom_palette
+			return false unless palette.is_a?(Array)
+			return palette.all? do |color| 
+				false unless color.is_a?(Array)
+				color.all? {|i| i.is_a?(Integer) }
+			end
+		end
 
     # Colors form Google Inbox
     # https://inbox.google.com
--
libgit2 0.21.0