diff --git a/sdpinfo.go b/sdpinfo.go
index f6d5555..8dada48 100644
--- a/sdpinfo.go
+++ b/sdpinfo.go
@@ -425,6 +425,11 @@ func (s *SDPInfo) String() string {
 		}
 
 		if strings.ToLower(media.mtype) == "application" {
+			mediaMap.SctpMap = &transform.SctpMapStuct{
+				5000,
+				"webrtc-datachannel",
+				1024,
+			}
 			mediaMap.Payloads = media.Payloads
 			mediaMap.SctpPort = 5000
 			mediaMap.SctpMaxSize = 256 * 1024
diff --git a/transform/grammer.go b/transform/grammer.go
index 7d42474..735b64d 100644
--- a/transform/grammer.go
+++ b/transform/grammer.go
@@ -529,9 +529,9 @@ var rulesMap map[byte][]*Rule = map[byte][]*Rule{
 			Format: "",
 			FormatFunc: func(obj *gabs.Container) string {
 				if hasValue(obj, "maxMessageSize") {
-					return "sctpmap:%s %s %s"
+					return "sctpmap:%d %s %d"
 				} else {
-					return "sctpmap:%s %s"
+					return "sctpmap:%d %s"
 				}
 			},
 		},
diff --git a/transform/sdpstruct.go b/transform/sdpstruct.go
index 26de3d6..71198cb 100644
--- a/transform/sdpstruct.go
+++ b/transform/sdpstruct.go
@@ -145,6 +145,7 @@ type MediaStruct struct {
 	Simulcast   *SimulcastStruct   `json:"simulcast,omitempty"`
 	SctpPort    int                `json:"sctp-port,omitempty"`
 	SctpMaxSize int                `json:"sctp-max-message-size,omitempty"`
+	SctpMap     *SctpMapStuct      `json:"sctpmap,omitempty"`
 }
 
 type SdpStruct struct {
@@ -159,3 +160,9 @@ type SdpStruct struct {
 	Connection   *ConnectionStruct   `json:"connection,omitempty"`
 	Icelite      string              `json:"icelite,omitempty"`
 }
+
+type SctpMapStuct struct {
+	Port           int       `json:"sctpmapNumber"`
+	App            string    `json:"app"`
+	MessageSize    int       `json:"maxMessageSize"`
+}