diff --git a/lib/devise.rb b/lib/devise.rb
index ede8038679..4aaba583c8 100644
--- a/lib/devise.rb
+++ b/lib/devise.rb
@@ -59,7 +59,7 @@ module Test
   NO_INPUT = []
 
   # True values used to check params
-  TRUE_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE']
+  TRUE_VALUES = [true, 1, '1', 'on', 't', 'T', 'true', 'TRUE']
 
   # Secret key used by the key generator
   mattr_accessor :secret_key