diff --git a/lib/pronounce.rb b/lib/pronounce.rb
index <HASH>..<HASH> 100644
--- a/lib/pronounce.rb
+++ b/lib/pronounce.rb
@@ -7,7 +7,10 @@ module Pronounce
   class << self
     def how_do_i_pronounce(word)
       @pronouncations ||= build_pronuciation_dictionary
-      @pronouncations[word.downcase].syllables.map {|syllable| syllable.as_strings }
+      word = word.downcase
+      if @pronouncations[word]
+        @pronouncations[word].syllables.map {|syllable| syllable.as_strings }
+      end
     end
 
     def symbols
diff --git a/spec/pronounce_spec.rb b/spec/pronounce_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/pronounce_spec.rb
+++ b/spec/pronounce_spec.rb
@@ -9,6 +9,10 @@ describe Pronounce do
     it 'groups the phones by syllable' do
       Pronounce.how_do_i_pronounce('monkeys').should == [['M', 'AH1', 'NG'], ['K', 'IY0', 'Z']]
     end
+
+    it 'returns nil for unknown words' do
+      Pronounce.how_do_i_pronounce('beeblebrox').should == nil
+    end
   end
 
   describe '#symbols' do
Return nil for unknown words as opposed to throwing an exception.