diff --git a/restapi.go b/restapi.go
index 476f783..9d53065 100644
--- a/restapi.go
+++ b/restapi.go
@@ -90,7 +90,7 @@ func (s *Session) RequestWithLockedBucket(method, urlStr, contentType string, b
 
 	req.Header.Set("Content-Type", contentType)
 	// TODO: Make a configurable static variable.
-	req.Header.Set("User-Agent", fmt.Sprintf("DiscordBot (https://github.com/bwmarrin/discordgo, v%s)", VERSION))
+	req.Header.Set("User-Agent", "DiscordBot (https://github.com/bwmarrin/discordgo, v"+VERSION+")")
 
 	if s.Debug {
 		for k, v := range req.Header {
@@ -250,7 +250,7 @@ func (s *Session) Register(username string) (token string, err error) {
 // even use.
 func (s *Session) Logout() (err error) {
 
-	//  _, err = s.Request("POST", LOGOUT, fmt.Sprintf(`{"token": "%s"}`, s.Token))
+	//  _, err = s.Request("POST", LOGOUT, `{"token": "` + s.Token + `"}`)
 
 	if s.Token == "" {
 		return
@@ -428,7 +428,7 @@ func (s *Session) UserGuilds(limit int, beforeID, afterID string) (st []*UserGui
 	uri := EndpointUserGuilds("@me")
 
 	if len(v) > 0 {
-		uri = fmt.Sprintf("%s?%s", uri, v.Encode())
+		uri += "?" + v.Encode()
 	}
 
 	body, err := s.RequestWithBucketID("GET", uri, nil, EndpointUserGuilds(""))
@@ -743,7 +743,7 @@ func (s *Session) GuildMembers(guildID string, after string, limit int) (st []*M
 	}
 
 	if len(v) > 0 {
-		uri = fmt.Sprintf("%s?%s", uri, v.Encode())
+		uri += "?" + v.Encode()
 	}
 
 	body, err := s.RequestWithBucketID("GET", uri, nil, EndpointGuildMembers(guildID))
@@ -1065,7 +1065,7 @@ func (s *Session) GuildPruneCount(guildID string, days uint32) (count uint32, er
 		Pruned uint32 `json:"pruned"`
 	}{}
 
-	uri := EndpointGuildPrune(guildID) + fmt.Sprintf("?days=%d", days)
+	uri := EndpointGuildPrune(guildID) + "?days=" + strconv.FormatUint(uint64(days), 10)
 	body, err := s.RequestWithBucketID("GET", uri, nil, EndpointGuildPrune(guildID))
 	if err != nil {
 		return
@@ -1423,7 +1423,7 @@ func (s *Session) ChannelMessages(channelID string, limit int, beforeID, afterID
 		v.Set("around", aroundID)
 	}
 	if len(v) > 0 {
-		uri = fmt.Sprintf("%s?%s", uri, v.Encode())
+		uri += "?" + v.Encode()
 	}
 
 	body, err := s.RequestWithBucketID("GET", uri, nil, EndpointChannelMessages(channelID))
@@ -2103,7 +2103,7 @@ func (s *Session) MessageReactions(channelID, messageID, emojiID string, limit i
 	}
 
 	if len(v) > 0 {
-		uri = fmt.Sprintf("%s?%s", uri, v.Encode())
+		uri += "?" + v.Encode()
 	}
 
 	body, err := s.RequestWithBucketID("GET", uri, nil, EndpointMessageReaction(channelID, "", "", ""))
diff --git a/types.go b/types.go
index 780b6bb..c0ce013 100644
--- a/types.go
+++ b/types.go
@@ -11,7 +11,6 @@ package discordgo
 
 import (
 	"encoding/json"
-	"fmt"
 	"net/http"
 	"time"
 )
@@ -54,5 +53,5 @@ func newRestError(req *http.Request, resp *http.Response, body []byte) *RESTErro
 }
 
 func (r RESTError) Error() string {
-	return fmt.Sprintf("HTTP %s, %s", r.Response.Status, r.ResponseBody)
+	return "HTTP " + r.Response.Status + ", " + string(r.ResponseBody)
 }
diff --git a/user.go b/user.go
index 618a7d5..a9af31a 100644
--- a/user.go
+++ b/user.go
@@ -1,9 +1,6 @@
 package discordgo
 
-import (
-	"fmt"
-	"strings"
-)
+import "strings"
 
 // A User stores all data for an individual Discord user.
 type User struct {
@@ -43,12 +40,12 @@ type User struct {
 
 // String returns a unique identifier of the form username#discriminator
 func (u *User) String() string {
-	return fmt.Sprintf("%s#%s", u.Username, u.Discriminator)
+	return u.Username + "#" + u.Discriminator
 }
 
 // Mention return a string which mentions the user
 func (u *User) Mention() string {
-	return fmt.Sprintf("<@%s>", u.ID)
+	return "<@" + u.ID + ">"
 }
 
 // AvatarURL returns a URL to the user's avatar.
diff --git a/voice.go b/voice.go
index 769e547..aaf7db5 100644
--- a/voice.go
+++ b/voice.go
@@ -14,6 +14,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -298,7 +299,7 @@ func (v *VoiceConnection) open() (err error) {
 	}
 
 	// Connect to VoiceConnection Websocket
-	vg := fmt.Sprintf("wss://%s", strings.TrimSuffix(v.endpoint, ":80"))
+	vg := "wss://" + strings.TrimSuffix(v.endpoint, ":80")
 	v.log(LogInformational, "connecting to voice endpoint %s", vg)
 	v.wsConn, _, err = websocket.DefaultDialer.Dial(vg, nil)
 	if err != nil {
@@ -541,7 +542,7 @@ func (v *VoiceConnection) udpOpen() (err error) {
 		return fmt.Errorf("empty endpoint")
 	}
 
-	host := fmt.Sprintf("%s:%d", strings.TrimSuffix(v.endpoint, ":80"), v.op2.Port)
+	host := strings.TrimSuffix(v.endpoint, ":80") + ":" + strconv.Itoa(v.op2.Port)
 	addr, err := net.ResolveUDPAddr("udp", host)
 	if err != nil {
 		v.log(LogWarning, "error resolving udp host %s, %s", host, err)