diff --git a/lib/enumerize/activemodel.rb b/lib/enumerize/activemodel.rb
index 7f2ad16..e0b590f 100644
--- a/lib/enumerize/activemodel.rb
+++ b/lib/enumerize/activemodel.rb
@@ -35,6 +35,10 @@ def initialize(attr)
       end
 
       def serialize(value)
+        if @attr.arguments[:multiple] && value.respond_to?(:map)
+          return @attr.find_values(*value).map(&:value)
+        end
+
         v = @attr.find_value(value)
         v && v.value
       end