diff --git a/notice.go b/notice.go
index af1c032..aa8818b 100644
--- a/notice.go
+++ b/notice.go
@@ -248,7 +248,13 @@ func DecodeRawNotice(r *RawNotice) (*Notice, error) {
 
 	var senderAddress net.IP
 	if len(r.HeaderFields) > senderSockaddrIndex {
-		ipBytes, err := DecodeZcode(r.HeaderFields[senderSockaddrIndex])
+		sockaddrField := r.HeaderFields[senderSockaddrIndex]
+		var ipBytes []byte
+		if len(sockaddrField) != 0 && sockaddrField[0] == 'Z' {
+			ipBytes, err = DecodeZcode(sockaddrField)
+		} else {
+			ipBytes, err = DecodeZAscii(sockaddrField)
+		}
 		if err != nil {
 			return nil, err
 		}
diff --git a/notice_test.go b/notice_test.go
index 29f574e..1c0b9c7 100644
--- a/notice_test.go
+++ b/notice_test.go
@@ -120,8 +120,16 @@ func TestDecodeNotice(t *testing.T) {
 	}
 
 	// Value in sender address takes precedence over UID value.
-	raw.HeaderFields[17] = []byte("Z\x08\x08\x08\x08")
-	expected.SenderAddress = net.ParseIP("8.8.8.8").To4()
+	raw.HeaderFields[17] = []byte("Z\xDE\xAD\xBE\xEF")
+	expected.SenderAddress = net.ParseIP("222.173.190.239").To4()
+	if notice, err := DecodeRawNotice(raw); err != nil {
+		t.Errorf("DecodeRawNotice(%v) failed: %v", raw, err)
+	} else {
+		expectNoticesEqual(t, notice, expected)
+	}
+
+	raw.HeaderFields[17] = []byte("0xDEADBEEF")
+	expected.SenderAddress = net.ParseIP("222.173.190.239").To4()
 	if notice, err := DecodeRawNotice(raw); err != nil {
 		t.Errorf("DecodeRawNotice(%v) failed: %v", raw, err)
 	} else {
diff --git a/raw_notice.go b/raw_notice.go
index 7c37603..6e4ac4d 100644
--- a/raw_notice.go
+++ b/raw_notice.go
@@ -130,7 +130,7 @@ const (
 	multipartIndex // string
 	multiuidIndex  // 12-byte zascii
 	// Added in 2009; no version bump
-	senderSockaddrIndex // zcode
+	senderSockaddrIndex // zcode or zascii
 	charsetIndex        // zascii16 little-endian
 	// Other fields
 	numKnownFields