diff --git a/CHANGES.md b/CHANGES.md
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,8 @@
+Version 2.0.1
+-------------
+
+* Added the universal gravitational constant, thanks to @hesiod.
+
 Version 2.0.0.1
 ---------------
 
diff --git a/Data/Constants/Mechanics.hs b/Data/Constants/Mechanics.hs
--- a/Data/Constants/Mechanics.hs
+++ b/Data/Constants/Mechanics.hs
@@ -24,3 +24,9 @@
 
 -- | Acceleration at Earth's surface due to gravity.
 declareConstant "gravity_g" 9.80665 [t| Meter :/ Second :^ Two |]
+
+-- | Gravitational constant (value recommended by CODATA, see the
+-- <http://arxiv.org/abs/1507.07956 arXiv> paper)
+declareConstant "gravity_G" 6.6740831e-11
+  [t| (Meter :^ Three) :* ((Kilo :@ Gram) :^ MOne) :* (Second :^ MTwo) |]
+  -- Thanks to @hesiod, PR #13
diff --git a/Data/Units/CGS.hs b/Data/Units/CGS.hs
--- a/Data/Units/CGS.hs
+++ b/Data/Units/CGS.hs
@@ -10,14 +10,14 @@
 -- Stability   :  experimental
 -- Portability :  non-portable
 --
--- This module defines units used in the centimeter/gram/second system
+-- This module defines units used in the centimeter\/gram\/second system
 -- of measurement.
 --
 -- Included are all mechanical units mentioned here:
 -- <http://en.wikipedia.org/wiki/Centimetre%E2%80%93gram%E2%80%93second_system_of_units>
 --
 -- Some electromagnetic units are not included, because these do not have
--- reliable conversions to/from the SI units, on which the @units-defs@
+-- reliable conversions to\/from the SI units, on which the @units-defs@
 -- edifice is based.
 -----------------------------------------------------------------------------
 
@@ -32,9 +32,13 @@
 import Data.Metrology.TH
 
 type Centimeter = Centi :@ Meter
+
+pattern Centimeter :: Centimeter
 pattern Centimeter = Centi :@ Meter
 
 type Centimetre = Centimeter
+
+pattern Centimetre :: Centimetre
 pattern Centimetre = Centimeter
 
 declareDerivedUnit "Gal"
diff --git a/Data/Units/SI.hs b/Data/Units/SI.hs
--- a/Data/Units/SI.hs
+++ b/Data/Units/SI.hs
@@ -37,11 +37,15 @@
 declareCanonicalUnit "Meter"   [t| Length |]                         (Just "m")
 
 type Metre = Meter
+
+pattern Metre :: Metre
 pattern Metre = Meter
 
 declareCanonicalUnit "Gram"    [t| Mass |]                           (Just "g")
 
 type Gramme = Gram
+
+pattern Gramme :: Gramme
 pattern Gramme = Gram
 
 declareCanonicalUnit "Second"  [t| Time |]                           (Just "s")
@@ -63,6 +67,8 @@
 declareDerivedUnit "Liter"     [t| (Centi :@ Meter) :^ Three |] 1000 (Just "L")
 
 type Litre = Liter
+
+pattern Litre :: Litre
 pattern Litre = Liter
 
 declareDerivedUnit "Newton"    [t| Gram :* Meter :/ (Second :^ Two) |]  1000  (Just "N")
@@ -91,6 +97,7 @@
 declareDerivedUnit "Ton"       [t| Kilo :@ Gram |]                      1000  (Just "t")
 
 type Tonne = Ton
+pattern Tonne :: Tonne
 pattern Tonne = Ton
 
 -- | A list of the names of all unit types. Useful with
@@ -103,4 +110,3 @@
   , ''Weber, ''Tesla, ''Henry, ''Lumen, ''Lux, ''Becquerel, ''Gray
   , ''Sievert, ''Katal, ''Hectare, ''Ton
   ]
-    
diff --git a/units-defs.cabal b/units-defs.cabal
--- a/units-defs.cabal
+++ b/units-defs.cabal
@@ -1,5 +1,5 @@
 name:           units-defs
-version:        2.0.0.1
+version:        2.0.1.1
 cabal-version:  >= 1.10
 synopsis:       Definitions for use with the units package
 homepage:       http://github.com/goldfirere/units-defs
@@ -22,11 +22,11 @@
 source-repository this
   type:     git
   location: https://github.com/goldfirere/units-defs.git
-  tag:      v2.0.0.1
+  tag:      v2.0.1.1
 
 library
   build-depends:      
-      base >= 4.7 && < 5,
+      base >= 4.8 && < 5,
       units >= 2.2 && < 3,
       template-haskell
   exposed-modules: