diff --git a/lib/ruby-measurement/definitions/us_customary/volume.rb b/lib/ruby-measurement/definitions/us_customary/volume.rb
index aeae6b3..ec56938 100644
--- a/lib/ruby-measurement/definitions/us_customary/volume.rb
+++ b/lib/ruby-measurement/definitions/us_customary/volume.rb
@@ -8,6 +8,8 @@
   unit.convert_to(:'fl oz') { |value| value * 128.0 }
   unit.convert_to(:tbsp) { |value| value * 256.0 }
   unit.convert_to(:tsp) { |value| value * 768.0 }
+  unit.convert_to(:ml) { |value| value * 3785.411784 }
+  unit.convert_to(:l) { |value| value * 3.785411784 }
 end
 
 Measurement.define(:'qt.') do |unit|
@@ -18,6 +20,8 @@
   unit.convert_to(:'fl oz') { |value| value * 32.0 }
   unit.convert_to(:tbsp) { |value| value * 64.0 }
   unit.convert_to(:tsp) { |value| value * 192.0 }
+  unit.convert_to(:ml) { |value| value * 946.352946 }
+  unit.convert_to(:l) { |value| value * 0.946352946 }
 end
 
 Measurement.define(:'pt.') do |unit|
@@ -28,6 +32,8 @@
   unit.convert_to(:'fl oz') { |value| value * 16.0 }
   unit.convert_to(:tbsp) { |value| value * 32.0 }
   unit.convert_to(:tsp) { |value| value * 96.0 }
+  unit.convert_to(:ml) { |value| value * 473.176473 }
+  unit.convert_to(:l) { |value| value * 0.473176473 }
 end
 
 Measurement.define(:'c.') do |unit|
@@ -38,6 +44,8 @@
   unit.convert_to(:'fl oz') { |value| value * 8.0 }
   unit.convert_to(:tbsp) { |value| value * 16.0 }
   unit.convert_to(:tsp) { |value| value * 48.0 }
+  unit.convert_to(:ml) { |value| value * 236.5882365 }
+  unit.convert_to(:l) { |value| value * 0.2365882365 }
 end
 
 Measurement.define(:'fl. oz.') do |unit|
@@ -48,6 +56,8 @@
   unit.convert_to(:c) { |value| value / 8.0 }
   unit.convert_to(:tbsp) { |value| value * 2.0 }
   unit.convert_to(:tsp) { |value| value * 6.0 }
+  unit.convert_to(:ml) { |value| value * 29.5735295625 }
+  unit.convert_to(:l) { |value| value * 0.0295735295625 }
 end
 
 Measurement.define(:'tbsp.') do |unit|
@@ -58,6 +68,8 @@
   unit.convert_to(:c) { |value| value / 16.0 }
   unit.convert_to(:'fl oz') { |value| value / 2.0 }
   unit.convert_to(:tsp) { |value| value * 3.0 }
+  unit.convert_to(:ml) { |value| value * 14.786764781 }
+  unit.convert_to(:l) { |value| value * 0.014786764781 }
 end
 
 Measurement.define(:'tsp.') do |unit|
@@ -68,4 +80,6 @@
   unit.convert_to(:c) { |value| value / 48.0 }
   unit.convert_to(:'fl oz') { |value| value / 6.0 }
   unit.convert_to(:tbsp) { |value| value / 3.0 }
+  unit.convert_to(:ml) { |value| value * 4.9289215938 }
+  unit.convert_to(:l) { |value| value * 0.0049289215938 }
 end
diff --git a/spec/ruby-measurement/core_ext/string_spec.rb b/spec/ruby-measurement/core_ext/string_spec.rb
index dd3adef..8b4521a 100644
--- a/spec/ruby-measurement/core_ext/string_spec.rb
+++ b/spec/ruby-measurement/core_ext/string_spec.rb
@@ -14,12 +14,12 @@
 
     describe 'with valid quantity and invalid unit' do
       subject { '3 people' }
-      specify { expect { subject.to_measurement }.to raise_error }
+      specify { expect { subject.to_measurement }.to raise_error(ArgumentError) }
     end
 
     describe 'with invalid input' do
       subject { 'foobar' }
-      specify { expect { subject.to_measurement }.to raise_error }
+      specify { expect { subject.to_measurement }.to raise_error(ArgumentError) }
     end
   end
 
@@ -31,7 +31,7 @@
 
     describe 'with invalid unit' do
       subject { 'person' }
-      specify { expect { subject.to_unit }.to raise_error }
+      specify { expect { subject.to_unit }.to raise_error(ArgumentError) }
     end
   end
 end
diff --git a/spec/ruby-measurement/core_ext/symbol_spec.rb b/spec/ruby-measurement/core_ext/symbol_spec.rb
index 0e41e54..cb2cfed 100644
--- a/spec/ruby-measurement/core_ext/symbol_spec.rb
+++ b/spec/ruby-measurement/core_ext/symbol_spec.rb
@@ -9,7 +9,7 @@
 
     describe 'with invalid unit' do
       subject { :person }
-      specify { expect { subject.to_unit }.to raise_error }
+      specify { expect { subject.to_unit }.to raise_error(ArgumentError) }
     end
   end
 end
diff --git a/spec/ruby-measurement/definitions/us_customary/volume_spec.rb b/spec/ruby-measurement/definitions/us_customary/volume_spec.rb
index fd78b3c..6f31e79 100644
--- a/spec/ruby-measurement/definitions/us_customary/volume_spec.rb
+++ b/spec/ruby-measurement/definitions/us_customary/volume_spec.rb
@@ -29,6 +29,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411784
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411784
+    end
   end
 
   describe 'quarts' do
@@ -57,6 +65,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411784
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411784
+    end
   end
 
   describe 'pints' do
@@ -85,6 +101,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411784
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411784
+    end
   end
 
   describe 'cups' do
@@ -113,6 +137,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411784
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411784
+    end
   end
 
   describe 'fluid ounces' do
@@ -141,6 +173,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411784
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411784
+    end
   end
 
   describe 'tablespoons' do
@@ -169,6 +209,14 @@
     it 'converts to teaspoons' do
       expect(subject.convert_to(:tsp).quantity).to eq 768
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.411783936
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.785411783936
+    end
   end
 
   describe 'teaspoons' do
@@ -197,5 +245,13 @@
     it 'converts to tablespoons' do
       expect(subject.convert_to(:tbsp).quantity).to eq 256
     end
+
+    it 'converts to milliliters' do
+      expect(subject.convert_to(:ml).quantity).to eq 3785.4117840384
+    end
+
+    it 'converts to liters' do
+      expect(subject.convert_to(:l).quantity).to eq 3.7854117840384
+    end
   end
 end
diff --git a/spec/ruby-measurement/measurement_spec.rb b/spec/ruby-measurement/measurement_spec.rb
index c2c16c2..846d0a2 100644
--- a/spec/ruby-measurement/measurement_spec.rb
+++ b/spec/ruby-measurement/measurement_spec.rb
@@ -38,13 +38,13 @@
 
     describe 'with invalid quantity' do
       it 'raises exception' do
-        expect { subject.new('hi') }.to raise_exception
+        expect { subject.new('hi') }.to raise_error(ArgumentError)
       end
     end
 
     describe 'with invalid unit' do
       it 'raises exception' do
-        expect { subject.new(3, :finklebaum) }.to raise_exception
+        expect { subject.new(3, :finklebaum) }.to raise_error(ArgumentError)
       end
     end
   end
@@ -146,7 +146,7 @@
       end
 
       it 'raises exception when undefined' do
-        expect { subject.parse('3 finklebaums') }.to raise_error
+        expect { subject.parse('3 finklebaums') }.to raise_error(ArgumentError)
       end
     end
   end
@@ -174,11 +174,11 @@
     end
 
     it 'raises exception if unit exists and is not convertable' do
-      expect { measurement.convert_to(:inches) }.to raise_error
+      expect { measurement.convert_to(:inches) }.to raise_error(ArgumentError)
     end
 
     it 'raises exception if unit does not exist' do
-      expect { measurement.convert_to(:finklebaum) }.to raise_error
+      expect { measurement.convert_to(:finklebaum) }.to raise_error(ArgumentError)
     end
   end
 
@@ -222,7 +222,7 @@
     it 'raises exception for incompatible units' do
       other = subject.new(4, :inches)
       expect(other.unit).to_not eq measurement.unit
-      expect { measurement + other }.to raise_error
+      expect { measurement + other }.to raise_error(ArgumentError)
     end
   end
 
@@ -256,7 +256,7 @@
     it 'raises exception for incompatible units' do
       other = subject.new(4, :inches)
       expect(other.unit).to_not eq measurement.unit
-      expect { measurement - other }.to raise_error
+      expect { measurement - other }.to raise_error(ArgumentError)
     end
   end
 
@@ -290,7 +290,7 @@
     it 'raises exception for incompatible units' do
       other = subject.new(4, :inches)
       expect(other.unit).to_not eq measurement.unit
-      expect { measurement * other }.to raise_error
+      expect { measurement * other }.to raise_error(ArgumentError)
     end
   end
 
@@ -324,7 +324,7 @@
     it 'raises exception for incompatible units' do
       other = subject.new(4, :inches)
       expect(other.unit).to_not eq measurement.unit
-      expect { measurement / other }.to raise_error
+      expect { measurement / other }.to raise_error(ArgumentError)
     end
   end
 
@@ -336,7 +336,7 @@
     end
 
     it 'raises exception for non-numeric values' do
-      expect { measurement ** subject.new(3) }.to raise_error
+      expect { measurement ** subject.new(3) }.to raise_error(ArgumentError)
     end
   end