diff --git a/lib/units-system.rb b/lib/units-system.rb
index <HASH>..<HASH> 100644
--- a/lib/units-system.rb
+++ b/lib/units-system.rb
@@ -556,18 +556,17 @@ module Units
   end
   
   
-  # Constant look-up was different in Ruby before 1.9.1
-  # In older Ruby versions, this must be included in any module or class from which units expressions
+  # This must be included in any module or class from which units expressions
   # are to be used in units or u blocks.
+  # It is not needed in Ruby 1.9.1 due to they way constant loop-up is done in that version,
+  # but Ruby 1.9.2 has changed that an requires this again.
   module UseBlocks
-    if RUBY_VERSION<"1.9"
-      def self.append_features(target)
-        def target.const_missing(name)
-          begin
-            Units.Measure(name)
-          rescue ArgumentError
-            super
-          end
+    def self.append_features(target)
+      def target.const_missing(name)
+        begin
+          Units.Measure(name)
+        rescue ArgumentError
+          super
         end
       end
     end
Adapt for Ruby <I> preview 3