diff --git a/cert_checker.go b/cert_checker.go
index 30a265a..629720f 100644
--- a/cert_checker.go
+++ b/cert_checker.go
@@ -65,7 +65,7 @@ func (c *ServerCheck) Check() error {
 	var f stanza.StreamFeatures
 	packet, err := stanza.NextPacket(decoder)
 	if err != nil {
-		err = fmt.Errorf("stream open decode features: %s", err)
+		err = fmt.Errorf("stream open decode features: %w", err)
 		return err
 	}
 
@@ -86,7 +86,7 @@ func (c *ServerCheck) Check() error {
 
 		var k stanza.TLSProceed
 		if err = decoder.DecodeElement(&k, nil); err != nil {
-			return fmt.Errorf("expecting starttls proceed: %s", err)
+			return fmt.Errorf("expecting starttls proceed: %w", err)
 		}
 
 		var tlsConfig tls.Config
diff --git a/stanza/parser.go b/stanza/parser.go
index b5f11cf..9017c97 100644
--- a/stanza/parser.go
+++ b/stanza/parser.go
@@ -91,7 +91,7 @@ func NextXmppToken(p *xml.Decoder) (xml.Token, error) {
 			return xml.StartElement{}, errors.New("connection closed")
 		}
 		if err != nil {
-			return xml.StartElement{}, fmt.Errorf("NextStart %s", err)
+			return xml.StartElement{}, fmt.Errorf("NextStart: %w", err)
 		}
 		switch t := t.(type) {
 		case xml.StartElement:
@@ -112,7 +112,7 @@ func NextStart(p *xml.Decoder) (xml.StartElement, error) {
 			return xml.StartElement{}, errors.New("connection closed")
 		}
 		if err != nil {
-			return xml.StartElement{}, fmt.Errorf("NextStart %s", err)
+			return xml.StartElement{}, fmt.Errorf("NextStart: %w", err)
 		}
 		switch t := t.(type) {
 		case xml.StartElement:
diff --git a/tcp_server_mock.go b/tcp_server_mock.go
index d189e3a..b74df04 100644
--- a/tcp_server_mock.go
+++ b/tcp_server_mock.go
@@ -131,7 +131,7 @@ func respondToIQ(t *testing.T, sc *ServerConn) {
 	// Decoder to parse the request
 	iqReq, err := receiveIq(sc)
 	if err != nil {
-		t.Fatalf("failed to receive IQ : %s", err.Error())
+		t.Fatalf("failed to receive IQ : %w", err.Error())
 	}
 
 	if vld, _ := iqReq.IsValid(); !vld {
@@ -155,7 +155,7 @@ func respondToIQ(t *testing.T, sc *ServerConn) {
 	mResp, err := xml.Marshal(iqResp)
 	_, err = fmt.Fprintln(sc.connection, string(mResp))
 	if err != nil {
-		t.Errorf("Could not send response stanza : %s", err)
+		t.Errorf("Could not send response stanza : %w", err)
 	}
 	return
 }
@@ -175,15 +175,15 @@ func discardPresence(t *testing.T, sc *ServerConn) {
 
 	if err != nil {
 		if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
-			t.Errorf("read timeout: %s", err)
+			t.Errorf("read timeout: %w", err)
 		} else {
-			t.Errorf("read error: %s", err)
+			t.Errorf("read error: %w", err)
 		}
 	}
 	err = xml.Unmarshal(recvBuf, &presenceStz)
 
 	if err != nil {
-		t.Errorf("Expected presence but this happened : %s", err.Error())
+		t.Errorf("Expected presence but this happened : %w", err.Error())
 	}
 }
 
@@ -223,7 +223,7 @@ func sendStreamFeatures(t *testing.T, sc *ServerConn) {
   </mechanisms>
 </stream:features>`
 	if _, err := fmt.Fprintln(sc.connection, features); err != nil {
-		t.Errorf("cannot send stream feature: %s", err)
+		t.Errorf("cannot send stream feature: %w", err)
 	}
 }
 
@@ -231,7 +231,7 @@ func sendStreamFeatures(t *testing.T, sc *ServerConn) {
 func readAuth(t *testing.T, decoder *xml.Decoder) string {
 	se, err := stanza.NextStart(decoder)
 	if err != nil {
-		t.Errorf("cannot read auth: %s", err)
+		t.Errorf("cannot read auth: %w", err)
 		return ""
 	}
 
@@ -239,7 +239,7 @@ func readAuth(t *testing.T, decoder *xml.Decoder) string {
 	nv = &stanza.SASLAuth{}
 	// Decode element into pointer storage
 	if err = decoder.DecodeElement(nv, &se); err != nil {
-		t.Errorf("cannot decode auth: %s", err)
+		t.Errorf("cannot decode auth: %w", err)
 		return ""
 	}
 
@@ -256,7 +256,7 @@ func sendBindFeature(t *testing.T, sc *ServerConn) {
   <bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>
 </stream:features>`
 	if _, err := fmt.Fprintln(sc.connection, features); err != nil {
-		t.Errorf("cannot send stream feature: %s", err)
+		t.Errorf("cannot send stream feature: %w", err)
 	}
 }
 
@@ -267,21 +267,21 @@ func sendRFC3921Feature(t *testing.T, sc *ServerConn) {
   <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
 </stream:features>`
 	if _, err := fmt.Fprintln(sc.connection, features); err != nil {
-		t.Errorf("cannot send stream feature: %s", err)
+		t.Errorf("cannot send stream feature: %w", err)
 	}
 }
 
 func bind(t *testing.T, sc *ServerConn) {
 	se, err := stanza.NextStart(sc.decoder)
 	if err != nil {
-		t.Errorf("cannot read bind: %s", err)
+		t.Errorf("cannot read bind: %w", err)
 		return
 	}
 
 	iq := &stanza.IQ{}
 	// Decode element into pointer storage
 	if err = sc.decoder.DecodeElement(&iq, &se); err != nil {
-		t.Errorf("cannot decode bind iq: %s", err)
+		t.Errorf("cannot decode bind iq: %w", err)
 		return
 	}
 
@@ -300,14 +300,14 @@ func bind(t *testing.T, sc *ServerConn) {
 func session(t *testing.T, sc *ServerConn) {
 	se, err := stanza.NextStart(sc.decoder)
 	if err != nil {
-		t.Errorf("cannot read session: %s", err)
+		t.Errorf("cannot read session: %w", err)
 		return
 	}
 
 	iq := &stanza.IQ{}
 	// Decode element into pointer storage
 	if err = sc.decoder.DecodeElement(&iq, &se); err != nil {
-		t.Errorf("cannot decode session iq: %s", err)
+		t.Errorf("cannot decode session iq: %w", err)
 		return
 	}