Type cast ActiveSupport::Duration before compiling it.

lib/devise/active_record.rb

@@ -60,9 +60,14 @@ module Devise
 
       # Convert new keys to methods which overwrites Devise defaults
       options.each do |key, value|
-        if value.is_a?(Proc)
+        case value
+          when Proc
             define_method key, &value
-        else
+            next
+          when ActiveSupport::Duration
+            value = value.to_i
+        end
+
         class_eval <<-END_EVAL, __FILE__, __LINE__
           def #{key}
             #{value.inspect}
@@ -70,7 +75,6 @@ module Devise
         END_EVAL
       end
     end
-    end
 
     # Stores all modules included inside the model, so we are able to verify
     # which routes are needed.