diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
--- a/.travis.yml
+++ /dev/null
@@ -1,97 +0,0 @@
-language: c
-sudo: false
-dist: trusty
-
-cache:
-  directories:
-    - $HOME/.cabsnap
-    - $HOME/.cabal/packages
-
-before_cache:
-  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/build-reports.log
-  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/00-index.tar
-
-matrix:
-  include:
-    - env: CABALVER=1.18 GHCVER=7.8.4 COVERAGE=1
-      compiler: ": #GHC 7.8.4"
-      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=1.22 GHCVER=7.10.3
-      compiler: ": #GHC 7.10.3"
-      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=8.0.2
-      compiler: ": #GHC 8.0.2"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.2,alex-3.1.4,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=2.0 GHCVER=8.2.2
-      compiler: ": #GHC 8.2.2"
-      addons: {apt: {packages: [cabal-install-2.0,ghc-8.2.2,alex-3.1.7,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=2.0 GHCVER=8.4.4
-      compiler: ": #GHC 8.4.4"
-      addons: {apt: {packages: [cabal-install-2.0,ghc-8.4.4,alex-3.1.7,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=2.4 GHCVER=8.6.5
-      compiler: ": #GHC 8.6.5"
-      addons: {apt: {packages: [cabal-install-2.4,ghc-8.6.5,alex-3.1.7,happy-1.19.5], sources: [hvr-ghc]}}
-    - env: CABALVER=2.4 GHCVER=8.8.3
-      compiler: ": #GHC 8.8.3"
-      addons: {apt: {packages: [cabal-install-2.4,ghc-8.8.3,alex-3.1.7,happy-1.19.5], sources: [hvr-ghc]}}
-
-before_install:
- - unset CC
- - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:/opt/alex/3.1.4/bin:/opt/happy/1.19.5/bin:~/.cabal/bin:$PATH
-
-install:
- - cabal --version
- - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
- - if [ -f $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz ];
-   then
-     zcat $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz >
-          $HOME/.cabal/packages/hackage.haskell.org/00-index.tar;
-   fi
- - travis_retry cabal update -v
- - sed -i 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config
- - cabal install --only-dependencies --enable-tests --enable-benchmarks --dry -v > installplan.txt
- - sed -i -e '1,/^Resolving /d' installplan.txt; cat installplan.txt
-
-# check whether current requested install-plan matches cached package-db snapshot
- - if diff -u installplan.txt $HOME/.cabsnap/installplan.txt;
-   then
-     echo "cabal build-cache HIT";
-     rm -rfv .ghc;
-     cp -a $HOME/.cabsnap/ghc $HOME/.ghc;
-     cp -a $HOME/.cabsnap/lib $HOME/.cabsnap/share $HOME/.cabsnap/bin $HOME/.cabal/;
-   else
-     echo "cabal build-cache MISS";
-     rm -rf $HOME/.cabsnap;
-     mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
-     cabal install --only-dependencies --enable-tests --enable-benchmarks;
-   fi
-
-# snapshot package-db on cache miss
- - if [ ! -d $HOME/.cabsnap ];
-   then
-      echo "snapshotting package-db to build-cache";
-      mkdir $HOME/.cabsnap;
-      cp -a $HOME/.ghc $HOME/.cabsnap/ghc;
-      cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin installplan.txt $HOME/.cabsnap/;
-   fi
-
-# Here starts the actual work to be performed for the package under test;
-# any command which exits with a non-zero exit code causes the build to fail.
-script:
- - if [ -f configure.ac ]; then autoreconf -i; fi
- - cabal configure --enable-tests --enable-benchmarks -v2 $([ "$COVERAGE" = "1" ] && echo "--enable-library-coverage") # -v2 provides useful information for debugging
- - cabal build   # this builds all libraries and executables (including tests/benchmarks)
- - cabal test
- - cabal check
- - cabal sdist   # tests that a source-distribution can be generated
-
-# Check that the resulting source distribution can be built & installed.
-# If there are no other `.tar.gz` files in `dist`, this can be even simpler:
-# `cabal install --force-reinstalls dist/*-*.tar.gz`
- - SRC_TGZ=$(cabal info . | awk '{print $2;exit}').tar.gz &&
-   (cd dist && cabal install --force-reinstalls "$SRC_TGZ")
-
-# This block must be executed before before_cache
-#after_script:
- - "[ -n \"$COVERAGE\" ] && cabal install hpc-coveralls --avoid-reinstalls --constraint=\"regex-posix >=0.95.2\" || true" # regex-posix-0.95.1 has compilation problem
- - "[ -n \"$COVERAGE\" ] && hpc-coveralls TestExtendedReal --exclude-dir=test || true"
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+# 0.2.5.0
+
+* add `fromRealFloat` helper
+
 # 0.2.4.0 (2020-03-28)
 
 * support GHC 8.4, 8.6, 8.8
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:             0.2.4.0
+version:             0.2.5.0
 synopsis:            Extension of real numbers with positive/negative infinities
 description:
   Extension of real numbers with positive/negative infinities (±∞).
@@ -11,26 +11,32 @@
 maintainer:          masahiro.sakai@gmail.com
 category:            Math
 build-type:          Simple
-extra-source-files:  .travis.yml, CHANGELOG.markdown
+extra-source-files:  CHANGELOG.markdown
 cabal-version:       >=1.10
 bug-reports:         https://github.com/msakai/extended-reals/issues
 tested-with:
-   GHC ==7.8.4
-   GHC ==7.10.3
    GHC ==8.0.2
    GHC ==8.2.2
    GHC ==8.4.4
    GHC ==8.6.5
-   GHC ==8.8.3
+   GHC ==8.8.4
+   GHC ==8.10.7
+   GHC ==9.0.2
+   GHC ==9.2.8
+   GHC ==9.4.8
+   GHC ==9.6.6
+   GHC ==9.8.4
+   GHC ==9.10.1
+   GHC ==9.12.1
 
 source-repository head
   type:     git
-  location: git://github.com/msakai/extended-reals.git
+  location: https://github.com/msakai/extended-reals.git
 
 library
   exposed-modules:     Data.ExtendedReal
   other-extensions:    DeriveDataTypeable
-  build-depends:       base >=4 && <5, deepseq >=1.3 && <1.5, hashable >=1.2 && <1.4
+  build-depends:       base >=4.9 && <5, deepseq >=1.3 && <1.6, hashable >=1.2 && <1.6
   hs-source-dirs:      src
   default-language:    Haskell2010
 
@@ -42,10 +48,10 @@
      base,
      deepseq,
      HUnit >=1.2 && <1.7,
-     QuickCheck >=2.6 && <2.15,
+     QuickCheck >=2.6 && <2.16,
      tasty >=0.10.1,
      tasty-hunit >=0.9 && <0.11,
-     tasty-quickcheck >=0.8 && <0.11,
+     tasty-quickcheck >=0.8 && <0.12,
      tasty-th,
      extended-reals
   Default-Language: Haskell2010
diff --git a/src/Data/ExtendedReal.hs b/src/Data/ExtendedReal.hs
--- a/src/Data/ExtendedReal.hs
+++ b/src/Data/ExtendedReal.hs
@@ -31,20 +31,22 @@
   , inf
   , isFinite
   , isInfinite
+  , fromRealFloat
   ) where
 
 import Prelude hiding (isInfinite)
+import qualified Prelude as P
 import Control.DeepSeq
-import Data.Data
+import Data.Data (Data)
 import Data.Hashable
-import Data.Typeable
+import Data.Typeable (Typeable)
 
 -- | @Extended r@ is an extension of /r/ with positive/negative infinity (±∞).
 data Extended r
   = NegInf    -- ^ negative infinity (-∞)
   | Finite !r -- ^ finite value
   | PosInf    -- ^ positive infinity (+∞)
-  deriving (Ord, Eq, Show, Read, Typeable, Data)
+  deriving (Ord, Eq, Show, Read, Data)
 
 instance Bounded (Extended r) where
   minBound = NegInf
@@ -133,3 +135,20 @@
         NegInf   -> PosInf
         Finite b -> Finite (a*b)
         PosInf   -> NegInf
+
+-- | Helper to convert 'Double' and 'Float' to 'Extended',
+-- taking care of infinite values automatically.
+--
+-- >>> fromRealFloat (1 / 0)
+-- PosInf
+-- >>> fromRealFloat (-1 / 0)
+-- NegInf
+-- >>> fromRealFloat (0 / 0)
+-- *** Exception: fromRealFloat: argument should not be NaN
+--
+-- @since 0.2.5.0
+fromRealFloat :: RealFloat r => r -> Extended r
+fromRealFloat x
+  | isNaN x = error "fromRealFloat: argument should not be NaN"
+  | P.isInfinite x = if x > 0 then PosInf else NegInf
+  | otherwise = Finite x