diff --git a/msg.go b/msg.go
index 294164ed..976deb74 100644
--- a/msg.go
+++ b/msg.go
@@ -69,7 +69,7 @@ type MsgHdr struct {
 // The layout of a DNS message.
 type Msg struct {
 	MsgHdr
-	Compress bool       // If true, the message will be compressed when converted to wire format.
+	Compress bool       `json:"-"` // If true, the message will be compressed when converted to wire format.
 	Question []Question // Holds the RR(s) of the question section.
 	Answer   []RR       // Holds the RR(s) of the answer section.
 	Ns       []RR       // Holds the RR(s) of the authority section.