diff --git a/libraries/base/GHC/IO/Encoding/Types.hs b/libraries/base/GHC/IO/Encoding/Types.hs
index d75bce31d032293ea81817f88f676f5e49a623fc..3dc7cd481e8e4972e23f7421335ff7dcb1137e6f 100644
--- a/libraries/base/GHC/IO/Encoding/Types.hs
+++ b/libraries/base/GHC/IO/Encoding/Types.hs
@@ -145,6 +145,7 @@ data CodingProgress = InputUnderflow  -- ^ Stopped because the input contains in
                              , Show -- ^ @since 4.4.0.0
                              )
 
+{-# COMPLETE BufferCodec #-}
 pattern BufferCodec :: CodeBuffer from to
                     -> (Buffer from -> Buffer to -> IO (Buffer from, Buffer to))
                     -> IO ()