money.diff

diff --git a/lib/money/money/arithmetic.rb b/lib/money/money/arithmetic.rb
index 38bc94e..19d6b79 100644
--- a/lib/money/money/arithmetic.rb
+++ b/lib/money/money/arithmetic.rb
@@ -125,10 +125,10 @@ class Money
     [:+, :-].each do |op|
       define_method(op) do |other|
         unless other.is_a?(Money)
-          if other.zero?
+          if other && other.zero?
             return other.is_a?(CoercedNumeric) ? Money.empty(currency).public_send(op, self) : self
           end
-          raise TypeError
+          raise TypeError, "Cannot perform arithemtic on non-zero value: #{other.inspect}"
         end
         other = other.exchange_to(currency)
         self.class.new(fractional.public_send(op, other.fractional), currency, bank)
diff --git a/spec/money/arithmetic_spec.rb b/spec/money/arithmetic_spec.rb
index 8856c9b..d04f3c2 100644
--- a/spec/money/arithmetic_spec.rb
+++ b/spec/money/arithmetic_spec.rb
@@ -218,6 +218,10 @@ describe Money do
       expect(special_money_class.new(10_00, "USD") + Money.new(90, "USD")).to be_a special_money_class
     end
 
+    it "raises TypeError when added to nil" do
+      expect { Money.zero + nil }.to raise_exception(TypeError)
+    end
+
     it_behaves_like 'instance with custom bank', :+, Money.new(1)
   end
 
@@ -241,6 +245,10 @@ describe Money do
       expect(special_money_class.new(10_00, "USD") - Money.new(90, "USD")).to be_a special_money_class
     end
 
+    it "raises TypeError when added to nil" do
+      expect { Money.zero - nil }.to raise_exception(TypeError)
+    end
+
     it_behaves_like 'instance with custom bank', :-, Money.new(1)
   end