diff --git a/lib/key_utilities.rb b/lib/key_utilities.rb
index 798e83f..6071c57 100644
--- a/lib/key_utilities.rb
+++ b/lib/key_utilities.rb
@@ -3,7 +3,7 @@ module KeyUtilities
   # generates a database unique api key
   def generate_api_key(size = 16)
     alphanumerics = ('0'..'9').to_a + ('A'..'Z').to_a
-    k = (0..size).map {alphanumerics[Kernel.rand(36)]}.join
+    k = (0..(size - 1)).map {alphanumerics[Kernel.rand(36)]}.join
   
     # if key exists in database, regenerate key
     k = generate_api_key if ApiKey.find_by_api_key(k)
@@ -11,4 +11,4 @@ module KeyUtilities
     # output the key
     k
   end
-end
\ No newline at end of file
+end