diff --git a/u_handshake_client.go b/u_handshake_client.go
index 8f198113..a848124f 100644
--- a/u_handshake_client.go
+++ b/u_handshake_client.go
@@ -100,7 +100,7 @@ func (hs *clientHandshakeStateTLS13) decompressCert(m utlsCompressedCertificateM
 	rawMsg[2] = uint8(m.uncompressedLength >> 8)
 	rawMsg[3] = uint8(m.uncompressedLength)
 
-	n, err := decompressed.Read(rawMsg[4:])
+	n, err := io.ReadFull(decompressed, rawMsg[4:])
 	if err != nil && !errors.Is(err, io.EOF) {
 		c.sendAlert(alertBadCertificate)
 		return nil, err