diff --git a/conn.go b/conn.go
index 866d5cd..49b4885 100644
--- a/conn.go
+++ b/conn.go
@@ -18,7 +18,8 @@ var connectedConnsMu sync.RWMutex
 type Conn struct {
 	*rudp.Conn
 
-	protoVer uint16
+	protoVer    uint16
+	formspecVer uint16
 
 	username string
 	srp_s    []byte
@@ -46,18 +47,18 @@ type Conn struct {
 	noClt    bool
 	modChs   map[string]bool
 
-	huds map[uint32]bool
-
+	huds   map[uint32]bool
 	sounds map[int32]bool
-
 	blocks [][3]int16
-
-	inv *mt.Inv
+	inv    *mt.Inv
 }
 
 // ProtoVer returns the protocol version of the Conn
 func (c *Conn) ProtoVer() uint16 { return c.protoVer }
 
+// FormspecVer returns the formspec API version of the Conn
+func (c *Conn) FormspecVer() uint16 { return c.formspecVer + 1 }
+
 // Addr returns the remote address of the Conn
 func (c *Conn) Addr() net.Addr {
 	return c.Conn.RemoteAddr()
diff --git a/init.go b/init.go
index 7f7484c..6d52a60 100644
--- a/init.go
+++ b/init.go
@@ -209,11 +209,14 @@ func Init(c, c2 *Conn, ignMedia, noAccessDenied bool, fin chan *Conn) {
 					continue
 				}
 
-				v := []byte("5.4.0-dev-dd5a732fa")
+				v := []byte("5.5.0-dev-83a7b48bb")
 
 				w := bytes.NewBuffer([]byte{0x00, ToServerClientReady})
 				w.Write([]byte{5, 4, 0, 0})
 				WriteBytes16(w, v)
+				if c.FormspecVer() != 1 {
+					WriteUint16(w, c.FormspecVer())
+				}
 
 				_, err := c2.Send(rudp.Pkt{
 					Reader: w,
@@ -535,6 +538,12 @@ func Init(c, c2 *Conn, ignMedia, noAccessDenied bool, fin chan *Conn) {
 					return
 				}
 
+				r.Seek(4, io.SeekCurrent)
+				ReadBytes16(r)
+				if r.Len() >= 2 {
+					c2.formspecVer = ReadUint16(r) - 1
+				}
+
 				defaultSrv := ConfKey("default_server").(string)
 
 				defSrv := func() *Conn {