diff --git a/lib/enumerize/attribute.rb b/lib/enumerize/attribute.rb
index b22bb7c..4790875 100644
--- a/lib/enumerize/attribute.rb
+++ b/lib/enumerize/attribute.rb
@@ -18,8 +18,12 @@ def initialize(klass, name, options={})
       value_class = options.fetch(:value_class, Value)
       @values = Array(options[:in]).map { |v| value_class.new(self, *v).freeze }
 
-      @value_hash = Hash[@values.map { |v| [v.value.to_s, v] }]
-      @value_hash.merge! Hash[@values.map { |v| [v.to_s, v] }]
+      # Two passes (value keys first, then name keys) so that name keys win on
+      # collision, matching the previous Hash#merge! behavior, without building
+      # the intermediate arrays and hashes that merge! required.
+      @value_hash = {}
+      @values.each { |v| @value_hash[v.value.to_s] = v }
+      @values.each { |v| @value_hash[v.to_s] = v }
 
       if options[:default]
         @default_value = find_default_value(options[:default])
diff --git a/lib/enumerize/value.rb b/lib/enumerize/value.rb
index a9672fc..a49c266 100644
--- a/lib/enumerize/value.rb
+++ b/lib/enumerize/value.rb
@@ -11,7 +11,11 @@ class Value < String
 
     def initialize(attr, name, value=nil)
       @attr  = attr
-      @value = value.nil? ? name.to_s : value
+      # Deduplicate the frozen string for plain-symbol enums so every value
+      # named e.g. "active" across the whole app shares one String object. It
+      # stays a plain (non-Value) String, so it's still safe to feed to
+      # write_attribute and friends.
+      @value = value.nil? ? -name.to_s : value
 
       super(name.to_s)