diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..d8be615
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,10 @@
+package melody
+
+import "errors"
+
+var (
+	ErrClosed            = errors.New("melody instance is closed")
+	ErrSessionClosed     = errors.New("session is closed")
+	ErrWriteClosed       = errors.New("tried to write to closed a session")
+	ErrMessageBufferFull = errors.New("session message buffer is full")
+)
diff --git a/melody.go b/melody.go
index 6123e77..e78055a 100644
--- a/melody.go
+++ b/melody.go
@@ -1,7 +1,6 @@
 package melody
 
 import (
-	"errors"
 	"net/http"
 	"sync"
 
@@ -164,7 +163,7 @@ func (m *Melody) HandleRequest(w http.ResponseWriter, r *http.Request) error {
 // HandleRequestWithKeys does the same as HandleRequest but populates session.Keys with keys.
 func (m *Melody) HandleRequestWithKeys(w http.ResponseWriter, r *http.Request, keys map[string]interface{}) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is closed")
+		return ErrClosed
 	}
 
 	conn, err := m.Upgrader.Upgrade(w, r, w.Header())
@@ -206,7 +205,7 @@ func (m *Melody) HandleRequestWithKeys(w http.ResponseWriter, r *http.Request, k
 // Broadcast broadcasts a text message to all sessions.
 func (m *Melody) Broadcast(msg []byte) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is closed")
+		return ErrClosed
 	}
 
 	message := &envelope{t: websocket.TextMessage, msg: msg}
@@ -218,7 +217,7 @@ func (m *Melody) Broadcast(msg []byte) error {
 // BroadcastFilter broadcasts a text message to all sessions that fn returns true for.
 func (m *Melody) BroadcastFilter(msg []byte, fn func(*Session) bool) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is closed")
+		return ErrClosed
 	}
 
 	message := &envelope{t: websocket.TextMessage, msg: msg, filter: fn}
@@ -247,7 +246,7 @@ func (m *Melody) BroadcastMultiple(msg []byte, sessions []*Session) error {
 // BroadcastBinary broadcasts a binary message to all sessions.
 func (m *Melody) BroadcastBinary(msg []byte) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is closed")
+		return ErrClosed
 	}
 
 	message := &envelope{t: websocket.BinaryMessage, msg: msg}
@@ -259,7 +258,7 @@ func (m *Melody) BroadcastBinary(msg []byte) error {
 // BroadcastBinaryFilter broadcasts a binary message to all sessions that fn returns true for.
 func (m *Melody) BroadcastBinaryFilter(msg []byte, fn func(*Session) bool) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is closed")
+		return ErrClosed
 	}
 
 	message := &envelope{t: websocket.BinaryMessage, msg: msg, filter: fn}
@@ -278,7 +277,7 @@ func (m *Melody) BroadcastBinaryOthers(msg []byte, s *Session) error {
 // Close closes the melody instance and all connected sessions.
 func (m *Melody) Close() error {
 	if m.hub.closed() {
-		return errors.New("melody instance is already closed")
+		return ErrClosed
 	}
 
 	m.hub.exit <- &envelope{t: websocket.CloseMessage, msg: []byte{}}
@@ -290,7 +289,7 @@ func (m *Melody) Close() error {
 // Use the FormatCloseMessage function to format a proper close message payload.
 func (m *Melody) CloseWithMsg(msg []byte) error {
 	if m.hub.closed() {
-		return errors.New("melody instance is already closed")
+		return ErrClosed
 	}
 
 	m.hub.exit <- &envelope{t: websocket.CloseMessage, msg: msg}
diff --git a/session.go b/session.go
index c34a785..2870591 100644
--- a/session.go
+++ b/session.go
@@ -1,7 +1,6 @@
 package melody
 
 import (
-	"errors"
 	"net/http"
 	"sync"
 	"time"
@@ -23,20 +22,20 @@ type Session struct {
 
 func (s *Session) writeMessage(message *envelope) {
 	if s.closed() {
-		s.melody.errorHandler(s, errors.New("tried to write to closed a session"))
+		s.melody.errorHandler(s, ErrWriteClosed)
 		return
 	}
 
 	select {
 	case s.output <- message:
 	default:
-		s.melody.errorHandler(s, errors.New("session message buffer is full"))
+		s.melody.errorHandler(s, ErrMessageBufferFull)
 	}
 }
 
 func (s *Session) writeRaw(message *envelope) error {
 	if s.closed() {
-		return errors.New("tried to write to a closed session")
+		return ErrWriteClosed
 	}
 
 	s.conn.SetWriteDeadline(time.Now().Add(s.melody.Config.WriteWait))
@@ -144,7 +143,7 @@ func (s *Session) readPump() {
 // Write writes message to session.
 func (s *Session) Write(msg []byte) error {
 	if s.closed() {
-		return errors.New("session is closed")
+		return ErrSessionClosed
 	}
 
 	s.writeMessage(&envelope{t: websocket.TextMessage, msg: msg})
@@ -155,7 +154,7 @@ func (s *Session) Write(msg []byte) error {
 // WriteBinary writes a binary message to session.
 func (s *Session) WriteBinary(msg []byte) error {
 	if s.closed() {
-		return errors.New("session is closed")
+		return ErrSessionClosed
 	}
 
 	s.writeMessage(&envelope{t: websocket.BinaryMessage, msg: msg})
@@ -166,7 +165,7 @@ func (s *Session) WriteBinary(msg []byte) error {
 // Close closes session.
 func (s *Session) Close() error {
 	if s.closed() {
-		return errors.New("session is already closed")
+		return ErrSessionClosed
 	}
 
 	s.writeMessage(&envelope{t: websocket.CloseMessage, msg: []byte{}})
@@ -178,7 +177,7 @@ func (s *Session) Close() error {
 // Use the FormatCloseMessage function to format a proper close message payload.
 func (s *Session) CloseWithMsg(msg []byte) error {
 	if s.closed() {
-		return errors.New("session is already closed")
+		return ErrSessionClosed
 	}
 
 	s.writeMessage(&envelope{t: websocket.CloseMessage, msg: msg})