diff --git a/Data/ByteString/Builder/RealFloat.hs b/Data/ByteString/Builder/RealFloat.hs
index 4a820b972..948fbc2cf 100644
--- a/Data/ByteString/Builder/RealFloat.hs
+++ b/Data/ByteString/Builder/RealFloat.hs
@@ -225,12 +225,14 @@ formatDouble = formatFloating
 {-# SPECIALIZE formatFloating :: FloatFormat -> Double -> Builder #-}
 formatFloating :: forall a mw ew ei.
   -- a
+  --( ToS a
   ( ToD a
+  , Num a
+  , Ord a
   , RealFloat a
-  , R.CastToWord a
-  , R.MantissaBits a
   , R.ExponentBits a
-  , Bits (R.ExponentWord a)
+  , R.MantissaBits a
+  , R.CastToWord a
   -- mantissa
   , mw ~ R.MantissaWord a
   , R.Mantissa mw
@@ -238,28 +240,23 @@ formatFloating :: forall a mw ew ei.
   , R.DecimalLength mw
   -- exponent
   , ew ~ R.ExponentWord a
-  , Integral (R.ExponentWord a)
+  , Integral ew
+  , Bits ew
   , ei ~ R.ExponentInt a
   , R.ToInt ei
   , Integral ei
   , R.FromInt ei
   ) => FloatFormat -> a -> Builder
 formatFloating fmt f = case fmt of
-  FGeneric eE prec (minExpo,maxExpo) ss ->
-    case R.toCharsNonNumbersAndZero ss f of
-      Just b -> BP.primBounded b ()
-      Nothing ->
-        if e' >= minExpo && e' <= maxExpo
-           then printSign f `mappend` showStandard (toWord64 m) e' prec
-           else BP.primBounded (sci eE) ()
-  FScientific eE ss -> flip BP.primBounded ()
-    $ fromMaybe (sci eE) (R.toCharsNonNumbersAndZero ss f)
-  FStandard prec ss ->
-    case R.toCharsNonNumbersAndZero ss f of
-      Just b -> BP.primBounded b ()
-      Nothing -> printSign f `mappend` showStandard (toWord64 m) e' prec
+  FGeneric eE prec (minExpo,maxExpo) ss -> flip fromMaybe (R.toCharsNonNumbersAndZero ss f) $
+    if e' >= minExpo && e' <= maxExpo
+       then printSign f `mappend` showStandard (toWord64 m) e' prec
+       else sci eE
+  FScientific eE ss -> fromMaybe (sci eE) (R.toCharsNonNumbersAndZero ss f)
+  FStandard prec ss -> flip fromMaybe (R.toCharsNonNumbersAndZero ss f) $
+    printSign f `mappend` showStandard (toWord64 m) e' prec
   where
-  sci eE = R.toCharsScientific @a Proxy eE sign m e
+  sci eE = BP.primBounded (R.toCharsScientific @a Proxy eE sign m e) ()
   e' = R.toInt e + R.decimalLength m
   R.FloatingDecimal m e = toD @a mantissa expo
   (sign, mantissa, expo) = R.breakdown f
diff --git a/Data/ByteString/Builder/RealFloat/Internal.hs b/Data/ByteString/Builder/RealFloat/Internal.hs
index 1e2e56bfe..acffac3e4 100644
--- a/Data/ByteString/Builder/RealFloat/Internal.hs
+++ b/Data/ByteString/Builder/RealFloat/Internal.hs
@@ -6,7 +6,6 @@
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE UndecidableInstances #-}
-{-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE BlockArguments #-}
@@ -89,9 +88,11 @@ module Data.ByteString.Builder.RealFloat.Internal
 import Control.Monad (foldM)
 import Data.Bits (Bits(..), FiniteBits(..))
 import Data.ByteString.Internal (c2w)
+import Data.ByteString.Builder.Internal (Builder)
 import Data.ByteString.Builder.Prim.Internal (BoundedPrim, boundedPrim)
 import Data.ByteString.Builder.RealFloat.TableGenerator
 import Data.ByteString.Utils.UnalignedWrite
+import qualified Data.ByteString.Builder.Prim as BP
 import Data.Char (ord)
 import Data.Proxy (Proxy)
 import Foreign.C.Types
@@ -265,19 +266,31 @@ boundString s = boundedPrim maxEncodedLength $ const (pokeAll s)
 --   * biased exponent = all 0 bits.
 --   * fraction = all 0 bits.
 {-# INLINABLE toCharsNonNumbersAndZero #-}
-{-# SPECIALIZE toCharsNonNumbersAndZero :: SpecialStrings -> Float -> Maybe (BoundedPrim ()) #-}
-{-# SPECIALIZE toCharsNonNumbersAndZero :: SpecialStrings -> Double -> Maybe (BoundedPrim ()) #-}
-toCharsNonNumbersAndZero :: forall a mw.
-  ( CastToWord a
-  , MantissaBits a
+{-# SPECIALIZE toCharsNonNumbersAndZero :: SpecialStrings -> Float -> Maybe Builder #-}
+{-# SPECIALIZE toCharsNonNumbersAndZero :: SpecialStrings -> Double -> Maybe Builder #-}
+toCharsNonNumbersAndZero :: forall a mw ew.
+  ( ExponentBits a
   , mw ~ MantissaWord a
   , Ord mw
   , Num mw
+  , ew ~ ExponentWord a
+  , Ord ew
+  , Num ew
+  , Bits ew
+  , Integral ew
+
+  , ExponentBits a
+  , MantissaBits a
+  , CastToWord a
+  , mw ~ MantissaWord a
   , Bits mw
+  , Eq mw
   , Integral mw
-  , ExponentBits a
-  ) => SpecialStrings -> a -> Maybe (BoundedPrim ())
-toCharsNonNumbersAndZero SpecialStrings{..} f = boundString <$>
+  , ew ~ ExponentWord a
+  , Num ew
+
+  ) => SpecialStrings -> a -> Maybe Builder
+toCharsNonNumbersAndZero SpecialStrings{..} f = flip BP.primBounded () . boundString <$>
   if w .&. expoMantissaBits == 0
   then Just if w == signBit then negativeZero else positiveZero
   else if w .&. expoMask == expoMask
@@ -943,6 +956,7 @@ breakdown :: forall a mw ew.
   , mw ~ MantissaWord a
   , Bits mw
   , Integral mw
+  , ew ~ ExponentWord a
   , Num ew
   ) => a -> (Bool, mw, ew)
 breakdown f = (sign, mantissa, expo)