diff --git a/lib/openhab/core/types/quantity_type.rb b/lib/openhab/core/types/quantity_type.rb
index 9dbcdab861..a23beb8556 100644
--- a/lib/openhab/core/types/quantity_type.rb
+++ b/lib/openhab/core/types/quantity_type.rb
@@ -180,15 +180,15 @@ def coerce(other)
             # def +(other)
             #   logger.trace("#{self} + #{other} (#{other.class})")
             #   if other.is_a?(QuantityType)
-            #     add_quantity(other)
+            #     add(other)
             #   elsif other.is_a?(DecimalType)
             #     other = other.to_big_decimal
-            #     add_quantity(self.class.new(other, DSL.unit(dimension) || unit))
+            #     add(self.class.new(other, DSL.unit(dimension) || unit))
             #   elsif other.is_a?(java.math.BigDecimal)
-            #     add_quantity(self.class.new(other, DSL.unit(dimension) || unit))
+            #     add(self.class.new(other, DSL.unit(dimension) || unit))
             #   elsif other.respond_to?(:to_d)
             #     other = other.to_d.to_java
-            #     add_quantity(self.class.new(other, DSL.unit(dimension) || unit))
+            #     add(self.class.new(other, DSL.unit(dimension) || unit))
             #   elsif other.respond_to?(:coerce) && (lhs, rhs = other.coerce(to_d))
             #     lhs + rhs
             #   else
@@ -199,15 +199,15 @@ def coerce(other)
               def #{ruby_op}(other)
                 logger.trace("\#{self} #{ruby_op} \#{other} (\#{other.class})")
                 if other.is_a?(QuantityType)
-                  #{java_op}_quantity(other)
+                  #{java_op}(other)
                 elsif other.is_a?(DecimalType)
                   other = other.to_big_decimal
-                  #{java_op}_quantity(#{convert})
+                  #{java_op}(#{convert})
                 elsif other.is_a?(java.math.BigDecimal)
-                  #{java_op}_quantity(#{convert})
+                  #{java_op}(#{convert})
                 elsif other.respond_to?(:to_d)
                   other = other.to_d.to_java
-                  #{java_op}_quantity(#{convert})
+                  #{java_op}(#{convert})
                 elsif other.respond_to?(:coerce) && (lhs, rhs = other.coerce(to_d))
                   lhs #{ruby_op} rhs
                 else
@@ -288,18 +288,6 @@ def deunitize
 
         private
 
-        # do addition directly against a QuantityType while ensuring we unitize
-        # both sides
-        def add_quantity(other)
-          unitize(other.unit).add(other.unitize(unit))
-        end
-
-        # do subtraction directly against a QuantityType while ensuring we
-        # unitize both sides
-        def subtract_quantity(other)
-          unitize(other.unit).subtract(other.unitize(unit))
-        end
-
         # do multiplication directly against a QuantityType while ensuring
         # we deunitize both sides, and also invert the operation if one side
         # isn't actually a unit
diff --git a/spec/openhab/core/types/quantity_type_spec.rb b/spec/openhab/core/types/quantity_type_spec.rb
index 5c5812991e..62cf9627d0 100644
--- a/spec/openhab/core/types/quantity_type_spec.rb
+++ b/spec/openhab/core/types/quantity_type_spec.rb
@@ -7,24 +7,45 @@
     expect(50.to_d | "°F").to eql QuantityType.new("50.0 °F") # rubocop:disable Performance/BigDecimalWithNumericArgument
   end
 
-  it "responds to math operations" do
-    # quantity type operand
-    expect(QuantityType.new("50 °F") + QuantityType.new("50 °F")).to eql QuantityType.new("100.0 °F")
-    expect(QuantityType.new("50 °F") - QuantityType.new("25 °F")).to eql QuantityType.new("25.0 °F")
-    expect((QuantityType.new("100 W") / QuantityType.new("2 W")).to_i).to be 50
-    expect(QuantityType.new("50 °F") + -QuantityType.new("25 °F")).to eql QuantityType.new("25.0 °F")
-
-    # numeric operand
-    expect(QuantityType.new("50 W") * 2).to eql QuantityType.new("100.0 W")
-    expect(QuantityType.new("100 W") / 2).to eql QuantityType.new("50.0 W")
-    expect(QuantityType.new("50 W") * 2.0).to eql QuantityType.new("100.0 W")
-    expect(QuantityType.new("100 W") / 2.0).to eql QuantityType.new("50.0 W")
-
-    # DecimalType operand
-    expect(QuantityType.new("50 W") * DecimalType.new(2)).to eql QuantityType.new("100.0 W")
-    expect(QuantityType.new("100 W") / DecimalType.new(2)).to eql QuantityType.new("50.0 W")
-    expect(QuantityType.new("50 W") * DecimalType.new(2.0)).to eql QuantityType.new("100.0 W")
-    expect(QuantityType.new("100 W") / DecimalType.new(2.0)).to eql QuantityType.new("50.0 W")
+  describe "math operations" do
+    it "supports quantity type operand" do
+      expect(QuantityType.new("50 °F") + QuantityType.new("50 °F")).to eql QuantityType.new("100.0 °F")
+      expect(QuantityType.new("50 °F") - QuantityType.new("25 °F")).to eql QuantityType.new("25.0 °F")
+      expect((QuantityType.new("100 W") / QuantityType.new("2 W")).to_i).to be 50
+      expect(QuantityType.new("50 °F") + -QuantityType.new("25 °F")).to eql QuantityType.new("25.0 °F")
+    end
+
+    it "supports numeric operand" do
+      expect(QuantityType.new("50 W") * 2).to eql QuantityType.new("100.0 W")
+      expect(QuantityType.new("100 W") / 2).to eql QuantityType.new("50.0 W")
+      expect(QuantityType.new("50 W") * 2.0).to eql QuantityType.new("100.0 W")
+      expect(QuantityType.new("100 W") / 2.0).to eql QuantityType.new("50.0 W")
+    end
+
+    it "supports DecimalType operand" do
+      expect(QuantityType.new("50 W") * DecimalType.new(2)).to eql QuantityType.new("100.0 W")
+      expect(QuantityType.new("100 W") / DecimalType.new(2)).to eql QuantityType.new("50.0 W")
+      expect(QuantityType.new("50 W") * DecimalType.new(2.0)).to eql QuantityType.new("100.0 W")
+      expect(QuantityType.new("100 W") / DecimalType.new(2.0)).to eql QuantityType.new("50.0 W")
+    end
+
+    describe "with mixed units" do
+      it "normalizes units in complex expression" do
+        expect(((23 | "°C") | "°F") - (70 | "°F")).to be < 4 | "°F"
+      end
+
+      it "supports arithmetic" do
+        expect((20 | "°C") + (9 | "°F")).to eql 25 | "°C"
+        expect((25 | "°C") - (9 | "°F")).to eql 20 | "°C"
+      end
+
+      it "works in a unit block" do
+        unit("°C") do
+          expect((20 | "°C") + (9 | "°F")).to eql 25 | "°C"
+          expect((25 | "°C") - (9 | "°F")).to eql 20 | "°C"
+        end
+      end
+    end
   end
 
   it "can be compared" do
@@ -71,10 +92,6 @@
     expect((0 | "W")..(10 | "W")).to cover(10 | "W")
   end
 
-  it "normalizes units in complex expression" do
-    expect(((23 | "°C") | "°F") - (70 | "°F")).to be < 4 | "°F"
-  end
-
   describe "comparisons" do
     let(:ten_c) { QuantityType.new("10 °C") }
     let(:five_c) { QuantityType.new("5 °C") }