diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@
 
 List of design decisions:
 
-* Keep everything at one place (Actually there are three modules; Intro.Trustworthy is needed for Safe Haskell)
+* Keep everything at one place
 * Conservative extension over the base Prelude
 * Rely only on common additional libraries
 * Avoid writing custom functions
diff --git a/intro.cabal b/intro.cabal
--- a/intro.cabal
+++ b/intro.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 name:           intro
-version:        0.8.0.0
+version:        0.9.0.0
 synopsis:       Safe and minimal prelude
 description:    Intro is a modern Prelude which provides safe alternatives
                 for most of the partial functions and follows other
@@ -22,7 +22,7 @@
 copyright:      2016-2017 Daniel Mendler
 license:        MIT
 license-file:   LICENSE
-tested-with:    GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.1
+tested-with:    GHC == 8.6.5, GHC == 8.8.1, GHC == 8.10.1
 build-type:     Simple
 extra-source-files:
     README.md
@@ -36,6 +36,7 @@
       Intro
   other-modules:
       Intro.ConvertString
+      Intro.ConvertIntegral
       Intro.Trustworthy
   hs-source-dirs:
       src
diff --git a/src/Intro.hs b/src/Intro.hs
--- a/src/Intro.hs
+++ b/src/Intro.hs
@@ -53,6 +53,13 @@
 -- * 'sequence' = 'Control.Applicative.sequenceA'
 -- * 'sequence_' = 'Control.Applicative.sequenceA_'
 --
+-- Integral type conversions are more restricted:
+--
+-- * 'toIntegral' is a safer, but more restricted version of 'fromIntegral'
+-- * 'toIntegerSized' is safe and checked
+-- * 'fromIntegralUnsafe' to get the unsafe, overflowing behavior
+-- * 'fromIntegerUnsafe' instead of 'fromInteger'
+--
 -- Unsafe functions are not provided. For example 'read' is replaced by 'readMaybe'.
 -- The unsafe list functions are replaced by their 'NonEmpty' counterparts. Furthermore '*May' and '*Def'
 -- functions are exported from the 'safe' package, e.g., 'headMay'.
@@ -306,7 +313,9 @@
   -- * Numeric type classes
 
   -- ** Num
-  , Prelude.Num((+), (-), (*), negate, abs, signum, fromInteger)
+  , Prelude.Num((+), (-), (*), negate, abs, signum
+      -- fromInteger
+      )
   , Prelude.subtract
   , (Prelude.^) -- partial functions!
 
@@ -316,7 +325,11 @@
 
   -- ** Integral
   , Prelude.Integral(quot, rem, div, mod, quotRem, divMod, toInteger) -- partial functions!
-  , Prelude.fromIntegral
+  , Intro.ConvertIntegral.ToIntegral(..)
+  , Data.Bits.toIntegralSized
+  , Intro.ConvertIntegral.fromIntegralUnsafe
+  , Intro.ConvertIntegral.fromIntegerUnsafe
+  --, Prelude.fromIntegral
   , Prelude.even
   , Prelude.odd
   --, Prelude.gcd
@@ -435,6 +448,15 @@
   , Control.Applicative.Const(Const, getConst) -- Data.Functor.Const
   , Data.Functor.Identity.Identity(Identity, runIdentity)
 
+  -- ** Contravariant
+  , Data.Functor.Contravariant.Contravariant(
+      (>$),
+      contramap
+      )
+  , (Data.Functor.Contravariant.$<)
+  , (Data.Functor.Contravariant.>$<)
+  , (Data.Functor.Contravariant.>$$<)
+
   -- ** Foldable
   , Data.Foldable.Foldable(elem, fold, foldMap,
            foldr, foldr',
@@ -661,6 +683,7 @@
 import Data.Semigroup (Semigroup((<>)))
 import Data.String (IsString(fromString), String)
 import Data.Text (Text)
+import Intro.ConvertIntegral
 import Intro.ConvertString
 import Intro.Trustworthy
 import System.IO (FilePath)
@@ -694,6 +717,7 @@
 import qualified Data.Functor
 import qualified Data.Functor.Classes
 import qualified Data.Functor.Identity
+import qualified Data.Functor.Contravariant
 import qualified Data.HashMap.Strict
 import qualified Data.HashSet
 import qualified Data.Hashable
@@ -930,4 +954,3 @@
 fail :: Control.Monad.Fail.MonadFail m => Text -> m a
 fail = Control.Monad.Fail.fail . convertString
 {-# INLINE fail #-}
-
diff --git a/src/Intro/ConvertIntegral.hs b/src/Intro/ConvertIntegral.hs
new file mode 100644
--- /dev/null
+++ b/src/Intro/ConvertIntegral.hs
@@ -0,0 +1,79 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Intro.ConvertInt
+-- Copyright   :  (c) Daniel Mendler 2020
+-- License     :  MIT
+--
+-- Maintainer  :  mail@daniel-mendler.de
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Integer conversion
+--
+-----------------------------------------------------------------------------
+
+{-# LANGUAGE Safe #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE DefaultSignatures #-}
+
+module Intro.ConvertIntegral (
+  ToIntegral(..)
+  , fromIntegralUnsafe
+  , fromIntegerUnsafe
+) where
+
+import Data.Int
+import Data.Word
+
+class ToIntegral a b where
+  toIntegral :: a -> b
+  default toIntegral :: (Integral a, Integral b) => a -> b
+  toIntegral = fromIntegral
+  {-# INLINE toIntegral #-}
+
+instance ToIntegral Word8 Int16
+instance ToIntegral Word8 Int32
+instance ToIntegral Word8 Int64
+instance ToIntegral Word8 Int
+instance ToIntegral Word16 Int32
+instance ToIntegral Word16 Int64
+instance ToIntegral Word16 Int
+instance ToIntegral Word32 Int64
+
+instance ToIntegral Word8 Word16
+instance ToIntegral Word8 Word32
+instance ToIntegral Word8 Word64
+instance ToIntegral Word8 Word
+instance ToIntegral Word16 Word32
+instance ToIntegral Word16 Word64
+instance ToIntegral Word16 Word
+instance ToIntegral Word32 Word64
+
+instance ToIntegral Int8 Integer
+instance ToIntegral Int16 Integer
+instance ToIntegral Int32 Integer
+instance ToIntegral Int64 Integer
+instance ToIntegral Int Integer
+
+instance ToIntegral Word8 Integer
+instance ToIntegral Word16 Integer
+instance ToIntegral Word32 Integer
+instance ToIntegral Word64 Integer
+instance ToIntegral Word Integer
+
+instance ToIntegral Int8 Int16
+instance ToIntegral Int8 Int32
+instance ToIntegral Int8 Int64
+instance ToIntegral Int8 Int
+instance ToIntegral Int16 Int32
+instance ToIntegral Int16 Int64
+instance ToIntegral Int16 Int
+instance ToIntegral Int32 Int64
+
+fromIntegralUnsafe :: (Integral a, Num b) => a -> b
+fromIntegralUnsafe = fromIntegral
+{-# INLINE fromIntegralUnsafe #-}
+
+fromIntegerUnsafe :: Num a => Integer -> a
+fromIntegerUnsafe = fromInteger
+{-# INLINE fromIntegerUnsafe #-}