diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 0e1057b..3a61821 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -12,7 +12,6 @@ on:
 jobs:
   build:
     strategy:
-      fail-fast: false
       matrix:
         include:
           - { os: ubuntu-20.04, ghc: 9.0.1, cabal: 3.4.0.0 }
@@ -48,3 +47,8 @@ jobs:
       - run: cabal check
       - if: github.event_name == 'release' && matrix.os == 'ubuntu-20.04' && matrix.ghc == '9.0.1'
         run: cabal upload --publish --username '${{ secrets.HACKAGE_USERNAME }}' --password '${{ secrets.HACKAGE_PASSWORD }}' dist-newstyle/sdist/witch-*.tar.gz
+  i386:
+     runs-on: ubuntu-20.04
+     steps:
+       - uses: actions/checkout@v2
+       - run: docker run --rm --user 0 --volume "$PWD:$PWD" --workdir "$PWD" taylorfausak/i386-haskell@sha256:450720742fa69258c0a8589dcac28c3c6d5d34718172d935b385520f4ee9128e sh -c 'cabal update && cabal test --test-show-details direct'
diff --git a/src/lib/Witch/Instances.hs b/src/lib/Witch/Instances.hs
index d4aa72a..8942f1b 100644
--- a/src/lib/Witch/Instances.hs
+++ b/src/lib/Witch/Instances.hs
@@ -251,7 +251,10 @@ instance TryFrom.TryFrom Int.Int64 Word where
 
 -- | Uses 'fromIntegral' when the input is not negative.
 instance TryFrom.TryFrom Int.Int64 Natural.Natural where
-  tryFrom = Utility.eitherTryFrom fromNonNegativeIntegral
+  -- This should use @eitherTryFrom fromNonNegativeIntegral@, but that causes
+  -- a bug in GHC 9.0.1.
+  -- https://mail.haskell.org/pipermail/haskell-cafe/2021-March/133540.html
+  tryFrom = Utility.eitherTryFrom $ \ s -> TryFrom.tryFrom (From.from s :: Integer)
 
 -- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
 -- inclusive.
@@ -590,7 +593,9 @@ instance TryFrom.TryFrom Word.Word64 Word where
 
 -- | Uses 'fromIntegral'.
 instance From.From Word.Word64 Natural.Natural where
-  from = fromIntegral
+  -- This should use @fromIntegral@, but that causes a bug in GHC 9.0.1.
+  -- https://mail.haskell.org/pipermail/haskell-cafe/2021-March/133540.html
+  from s = Utility.unsafeFrom (From.from s :: Integer)
 
 -- | Uses 'Bits.toIntegralSized'.
 instance TryFrom.TryFrom Word.Word64 Int.Int8 where
diff --git a/src/test/Main.hs b/src/test/Main.hs
index d886606..4bef51a 100644
--- a/src/test/Main.hs
+++ b/src/test/Main.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -Wno-error=overflowed-literals #-}
+
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE TypeApplications #-}
@@ -363,8 +365,12 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Int64 Int" ~:
       let f = hush . Witch.tryFrom @Int.Int64 @Int in
       [ f 0 ~?= Just 0
-      , f 9223372036854775807 ~?= Just 9223372036854775807
-      , f (-9223372036854775808) ~?= Just (-9223372036854775808)
+      , let x = maxBound :: Int in if toInteger x >= 9223372036854775807
+        then f 9223372036854775807 ~?= Just 9223372036854775807
+        else f (fromIntegral x) ~?= Just x
+      , let x = minBound :: Int in if toInteger x <= (-9223372036854775808)
+        then f (-9223372036854775808) ~?= Just (-9223372036854775808)
+        else f (fromIntegral x) ~?= Just x
       ]
     , "From Int64 Integer" ~:
       let f = Witch.from @Int.Int64 @Integer in
@@ -401,7 +407,9 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Int64 Word" ~:
       let f = hush . Witch.tryFrom @Int.Int64 @Word in
       [ f 0 ~?= Just 0
-      , f 9223372036854775807 ~?= Just 9223372036854775807
+      , let x = maxBound :: Word in if toInteger x >= 9223372036854775807
+        then f 9223372036854775807 ~?= Just 9223372036854775807
+        else f (fromIntegral x) ~?= Just x
       , f (-1) ~?= Nothing
       ]
     , "TryFrom Int64 Natural" ~:
@@ -446,9 +454,13 @@ main = runTestTTAndExit $ "Witch" ~:
       let f = hush . Witch.tryFrom @Int @Int.Int32 in
       [ f 0 ~?= Just 0
       , f 2147483647 ~?= Just 2147483647
-      , f 2147483648 ~?= Nothing
+      , let x = maxBound :: Int in if toInteger x >= 2147483648
+        then f 2147483648 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       , f (-2147483648) ~?= Just (-2147483648)
-      , f (-2147483649) ~?= Nothing
+      , let x = minBound :: Int in if toInteger x <= (-2147483649)
+        then f (-2147483649) ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       ]
     , "From Int Int64" ~:
       let f = Witch.from @Int @Int.Int64 in
@@ -479,8 +491,12 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Int Word32" ~:
       let f = hush . Witch.tryFrom @Int @Word.Word32 in
       [ f 0 ~?= Just 0
-      , f 4294967295 ~?= Just 4294967295
-      , f 4294967296 ~?= Nothing
+      , let x = maxBound :: Int in if toInteger x >= 4294967295
+        then f 4294967295 ~?= Just 4294967295
+        else f x ~?= Just (fromIntegral x)
+      , let x = maxBound :: Int in if toInteger x >= 4294967296
+        then f 4294967296 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       , f (-1) ~?= Nothing
       ]
     , "TryFrom Int Word64" ~:
@@ -512,10 +528,18 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Int Double" ~:
       let f = hush . Witch.tryFrom @Int @Double in
       [ f 0 ~?= Just 0
-      , f 9007199254740991 ~?= Just 9007199254740991
-      , f 9007199254740992 ~?= Nothing
-      , f (-9007199254740991) ~?= Just (-9007199254740991)
-      , f (-9007199254740992) ~?= Nothing
+      , let x = maxBound :: Int in if toInteger x >= 9007199254740991
+        then f 9007199254740991 ~?= Just 9007199254740991
+        else f x ~?= Just (fromIntegral x)
+      , let x = maxBound :: Int in if toInteger x >= 9007199254740992
+        then f 9007199254740992 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
+      , let x = minBound :: Int in if toInteger x <= (-9007199254740991)
+        then f (-9007199254740991) ~?= Just (-9007199254740991)
+        else f x ~?= Just (fromIntegral x)
+      , let x = minBound :: Int in if toInteger x <= (-9007199254740992)
+        then f (-9007199254740992) ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       ]
     , "TryFrom Integer Int8" ~:
       let f = hush . Witch.tryFrom @Integer @Int.Int8 in
@@ -801,7 +825,9 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Word32 Int" ~:
       let f = hush . Witch.tryFrom @Word.Word32 @Int in
       [ f 0 ~?= Just 0
-      , f 4294967295 ~?= Just 4294967295
+      , let x = maxBound :: Int in if toInteger x >= 4294967295
+        then f 4294967295 ~?= Just 4294967295
+        else f (fromIntegral x) ~?= Just x
       ]
     , "From Word32 Integer" ~:
       let f = Witch.from @Word.Word32 @Integer in
@@ -840,7 +866,9 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Word64 Word" ~:
       let f = hush . Witch.tryFrom @Word.Word64 @Word in
       [ f 0 ~?= Just 0
-      , f 18446744073709551615 ~?= Just 18446744073709551615
+      , let x = maxBound :: Word in if toInteger x >= 18446744073709551615
+        then f 18446744073709551615 ~?= Just 18446744073709551615
+        else f (fromIntegral x) ~?= Just x
       ]
     , "From Word64 Natural" ~:
       let f = Witch.from @Word.Word64 @Natural.Natural in
@@ -910,7 +938,9 @@ main = runTestTTAndExit $ "Witch" ~:
       let f = hush . Witch.tryFrom @Word @Word.Word32 in
       [ f 0 ~?= Just 0
       , f 4294967295 ~?= Just 4294967295
-      , f 4294967296 ~?= Nothing
+      , let x = maxBound :: Word in if toInteger x >= 4294967296
+        then f 4294967296 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       ]
     , "From Word Word64" ~:
       let f = Witch.from @Word @Word.Word64 in
@@ -943,8 +973,12 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Word Int64" ~:
       let f = hush . Witch.tryFrom @Word @Int.Int64 in
       [ f 0 ~?= Just 0
-      , f 9223372036854775807 ~?= Just 9223372036854775807
-      , f 9223372036854775808 ~?= Nothing
+      , let x = maxBound :: Word in if toInteger x >= 9223372036854775807
+        then f 9223372036854775807 ~?= Just 9223372036854775807
+        else f x ~?= Just (fromIntegral x)
+      , let x = maxBound :: Word in if toInteger x >= 9223372036854775808
+        then f 9223372036854775808 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       ]
     , "TryFrom Word Int" ~:
       let f = hush . Witch.tryFrom @Word @Int in
@@ -966,8 +1000,12 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Word Double" ~:
       let f = hush . Witch.tryFrom @Word @Double in
       [ f 0 ~?= Just 0
-      , f 9007199254740991 ~?= Just 9007199254740991
-      , f 9007199254740992 ~?= Nothing
+      , let x = maxBound :: Word in if toInteger x >= 9007199254740991
+        then f 9007199254740991 ~?= Just 9007199254740991
+        else f x ~?= Just (fromIntegral x)
+      , let x = maxBound :: Word in if toInteger x >= 9007199254740992
+        then f 9007199254740992 ~?= Nothing
+        else f x ~?= Just (fromIntegral x)
       ]
     , "TryFrom Natural Word8" ~:
       let f = hush . Witch.tryFrom @Natural.Natural @Word.Word8 in
@@ -1236,9 +1274,13 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Double Int" ~:
       let f = hush . Witch.tryFrom @Double @Int in
       [ f 0 ~?= Just 0
-      , f 9007199254740991 ~?= Just 9007199254740991
+      , let x = maxBound :: Int in if toInteger x >= 9007199254740991
+        then f 9007199254740991 ~?= Just 9007199254740991
+        else f (fromIntegral x) ~?= Just x
       , f 9007199254740992 ~?= Nothing
-      , f (-9007199254740991) ~?= Just (-9007199254740991)
+      , let x = minBound :: Int in if toInteger x <= (-9007199254740991)
+        then f (-9007199254740991) ~?= Just (-9007199254740991)
+        else f (fromIntegral x) ~?= Just x
       , f (-9007199254740992) ~?= Nothing
       , f (0 / 0) ~?= Nothing
       , f (1 / 0) ~?= Nothing
@@ -1294,7 +1336,9 @@ main = runTestTTAndExit $ "Witch" ~:
     , "TryFrom Double Word" ~:
       let f = hush . Witch.tryFrom @Double @Word in
       [ f 0 ~?= Just 0
-      , f 9007199254740991 ~?= Just 9007199254740991
+      , let x = maxBound :: Word in if toInteger x >= 9007199254740991
+        then f 9007199254740991 ~?= Just 9007199254740991
+        else f (fromIntegral x) ~?= Just x
       , f 9007199254740992 ~?= Nothing
       , f (0 / 0) ~?= Nothing
       , f (1 / 0) ~?= Nothing