diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.markdown
@@ -0,0 +1,3 @@
+0.2.0.0
+-----
+* add 'inf' as a short-hand for PosInf
diff --git a/extended-reals.cabal b/extended-reals.cabal
--- a/extended-reals.cabal
+++ b/extended-reals.cabal
@@ -1,5 +1,5 @@
 name:                extended-reals
-version:             0.1.0.0
+version:             0.2.0.0
 synopsis:            Extension of real numbers with positive/negative infinities
 description:
   Extension of real numbers with positive/negative infinities (±∞).
@@ -11,7 +11,7 @@
 maintainer:          masahiro.sakai@gmail.com
 category:            Math
 build-type:          Simple
-extra-source-files:  .travis.yml
+extra-source-files:  .travis.yml, CHANGELOG.markdown
 cabal-version:       >=1.10
 bug-reports:         https://github.com/msakai/extended-reals/issues
 
diff --git a/src/Data/ExtendedReal.hs b/src/Data/ExtendedReal.hs
--- a/src/Data/ExtendedReal.hs
+++ b/src/Data/ExtendedReal.hs
@@ -28,6 +28,7 @@
 -----------------------------------------------------------------------------
 module Data.ExtendedReal
   ( Extended (..)
+  , inf
   , isFinite
   , isInfinite
   ) where
@@ -62,6 +63,10 @@
   hashWithSalt s NegInf     = s `hashWithSalt` (0::Int)
   hashWithSalt s (Finite x) = s `hashWithSalt` (1::Int) `hashWithSalt` x
   hashWithSalt s PosInf     = s `hashWithSalt` (2::Int)
+
+-- | Infinity (∞)
+inf :: Extended r
+inf = PosInf
 
 -- | @isFinite x = not (isInfinite x)@.
 isFinite :: Extended r -> Bool
diff --git a/test/TestExtendedReal.hs b/test/TestExtendedReal.hs
--- a/test/TestExtendedReal.hs
+++ b/test/TestExtendedReal.hs
@@ -71,7 +71,7 @@
 -- PosInf + NegInf is left undefined
 case_add_PosInf_NegInf :: IO ()
 case_add_PosInf_NegInf =
-  eval (PosInf + NegInf :: Extended Rational) @?= Nothing
+  eval (inf + (- inf) :: Extended Rational) @?= Nothing
 
 prop_mult_assoc :: Property
 prop_mult_assoc =
@@ -109,12 +109,12 @@
 -- We define 0 * PosInf = 0
 case_mult_zero_PosInf :: IO ()
 case_mult_zero_PosInf =
-  0 * PosInf @?= (0 :: Extended Rational)
+  0 * inf @?= (0 :: Extended Rational)
 
 -- We define 0 * NegInf = 0
 case_mult_zero_NegInf :: IO ()
 case_mult_zero_NegInf =
-  0 * NegInf @?= (0 :: Extended Rational)
+  0 * (- inf) @?= (0 :: Extended Rational)
 
 prop_negate_inverse :: Property
 prop_negate_inverse = 
@@ -132,20 +132,20 @@
     isFinite a && a /= 0 ==> recip (recip a) == a
 
 case_recip_PosInf :: IO ()
-case_recip_PosInf = recip PosInf @?= (0 :: Extended Rational)
+case_recip_PosInf = recip inf @?= (0 :: Extended Rational)
 
 case_recip_NegInf :: IO ()
-case_recip_NegInf = recip NegInf @?= (0 :: Extended Rational)
+case_recip_NegInf = recip (- inf) @?= (0 :: Extended Rational)
 
 prop_NegInf_smallest :: Property
 prop_NegInf_smallest =
   forAll arbitrary $ \(a :: Extended Rational) ->
-    NegInf <= a
+    -inf <= a
 
 prop_PosInf_largest :: Property
 prop_PosInf_largest =
   forAll arbitrary $ \(a :: Extended Rational) ->
-    a <= PosInf
+    a <= inf
 
 -- ----------------------------------------------------------------------
 -- Test harness