diff --git a/lib/unitwise/scale.rb b/lib/unitwise/scale.rb
index <HASH>..<HASH> 100644
--- a/lib/unitwise/scale.rb
+++ b/lib/unitwise/scale.rb
@@ -94,6 +94,10 @@ module Unitwise
     end
     memoize :simplified_value
 
+    def expression
+      unit.expression
+    end
+
     # Convert to a simple string representing the scale.
     # @api public
     def to_s
diff --git a/test/unitwise/measurement_test.rb b/test/unitwise/measurement_test.rb
index <HASH>..<HASH> 100644
--- a/test/unitwise/measurement_test.rb
+++ b/test/unitwise/measurement_test.rb
@@ -13,7 +13,7 @@ describe Unitwise::Measurement do
 
   describe "#convert_to" do
     it "must convert to a similar unit code" do
-      mph.convert_to('km/h').value.must_almost_equal 96.56063
+      mph.convert_to('km/h').value.must_almost_equal(96.56063)
     end
     it "must raise an error if the units aren't similar" do
       lambda { mph.convert_to('N') }.must_raise Unitwise::ConversionError
@@ -33,6 +33,9 @@ describe Unitwise::Measurement do
     it "must convert derived units to special units" do
       r.convert_to("Cel").value.must_almost_equal(0)
     end
+    it "must convert to a unit of another measurement" do
+      mph.convert_to(kmh).value.must_almost_equal(96.56064)
+    end
   end
 
   describe "#*" do
May now convert measurements to units of other measurements.