diff --git a/src/Data/ByteArray/Builder/Bounded/Unsafe.hs b/src/Data/ByteArray/Builder/Bounded/Unsafe.hs
index 9bad04f..5d5e58c 100644
--- a/src/Data/ByteArray/Builder/Bounded/Unsafe.hs
+++ b/src/Data/ByteArray/Builder/Bounded/Unsafe.hs
@@ -27,8 +27,11 @@ import Data.Primitive (MutableByteArray(..))
 -- when executed.
 newtype Builder :: Nat -> Type where
    Builder ::
-        (forall s. MutableByteArray# s -> Int# -> State# s -> (# State# s, Int# #))
+        (forall s. MutableByteArray# s -> Int# -> State# s -> (# State# s, Int# #)) 
+        -- ^ This function takes a buffer, an offset, and a number of remaining bytes.
+        --   It returns the new offset.
      -> Builder n
+   
 
 -- | Constructor for 'Builder' that works on a function with lifted
 -- arguments instead of unlifted ones. This is just as unsafe as the
diff --git a/src/Data/ByteArray/Builder/Unsafe.hs b/src/Data/ByteArray/Builder/Unsafe.hs
index 18c2eba..844cf83 100644
--- a/src/Data/ByteArray/Builder/Unsafe.hs
+++ b/src/Data/ByteArray/Builder/Unsafe.hs
@@ -31,10 +31,11 @@ import qualified Data.ByteArray.Builder.Bounded.Unsafe as UnsafeBounded
 
 -- | An unmaterialized sequence of bytes that may be pasted
 -- into a mutable byte array.
-newtype Builder = Builder
-  -- This functions takes an offset and a number of remaining bytes
-  -- and returns the new offset.
-  (forall s. MutableByteArray# s -> Int# -> Int# -> State# s -> (# State# s, Int# #))
+newtype Builder
+  = Builder (forall s. MutableByteArray# s -> Int# -> Int# -> State# s -> (# State# s, Int# #))
+    -- ^ This function takes a buffer, an offset, and a number of remaining bytes.
+    --   It returns the new offset (should be greater than the old offset), or if
+    --   there was not enough space left in buffer, it returns -1.
 
 instance IsString Builder where
   {-# inline fromString #-}