@@ -46,7 +46,9 @@ bytea = putByteString
 
 {-# INLINE char #-}
 char :: Char -> Encode
-char = putWord8 . fromIntegral . ord
+char c
+| ord(c) >= 128 = error "Character code must be below 128"
+| otherwise = (putWord8 . fromIntegral . ord) c
 
 {-# INLINE date #-}
 date :: Day -> Encode

@@ -95,17 +95,18 @@ testCodecsEncodeDecode :: TestTree
 testCodecsEncodeDecode = testGroup "Codecs property 'encode . decode = id'"
 [ mkCodecTest "bool" PGT.bool PE.bool PD.bool
 , mkCodecTest "bytea" PGT.bytea PE.bytea PD.bytea
-, mkCodecTest "char" PGT.char PE.char PD.char
+, mkCodecTest "char" PGT.char (PE.char . unAsciiChar)
+(fmap AsciiChar <$> PD.char)
 , mkCodecTest "date" PGT.date PE.date PD.date
 , mkCodecTest "float4" PGT.float4 PE.float4 PD.float4
 , mkCodecTest "float8" PGT.float8 PE.float8 PD.float8
 , mkCodecTest "int2" PGT.int2 PE.int2 PD.int2
 , mkCodecTest "int4" PGT.int4 PE.int4 PD.int4
 , mkCodecTest "int8" PGT.int8 PE.int8 PD.int8
 , mkCodecTest "interval" PGT.interval PE.interval PD.interval
-, mkCodecTest "json" PGT.json (PE.bsJsonText . unJsonString )
+, mkCodecTest "json" PGT.json (PE.bsJsonText . unJsonString)
 (fmap JsonString <$> PD.bsJsonText)
-, mkCodecTest "jsonb" PGT.jsonb (PE.bsJsonBytes .unJsonString)
+, mkCodecTest "jsonb" PGT.jsonb (PE.bsJsonBytes . unJsonString)
 (fmap JsonString <$> PD.bsJsonBytes)
 , mkCodecTest "numeric" PGT.numeric PE.numeric PD.numeric
 , mkCodecTest "text" PGT.text PE.bsText PD.bsText
@@ -145,6 +146,12 @@ testCodecsEncodePrint = testGroup
 -- Orphan instances
 --
 
+newtype AsciiChar = AsciiChar { unAsciiChar :: Char }
+deriving (Show, Eq)
+
+instance Arbitrary AsciiChar where
+arbitrary = AsciiChar <$> choose ('\0', '\127')
+
 -- Helper to generate valid json strings
 newtype JsonString = JsonString { unJsonString :: B.ByteString }
 deriving (Show, Eq, IsString)