diff --git a/cmd/strelaysrv/utils.go b/cmd/strelaysrv/utils.go
index 66a472586..39d04fc44 100644
--- a/cmd/strelaysrv/utils.go
+++ b/cmd/strelaysrv/utils.go
@@ -10,7 +10,7 @@ import (
 func setTCPOptions(conn net.Conn) error {
 	tcpConn, ok := conn.(*net.TCPConn)
 	if !ok {
-		return errors.New("Not a TCP connection")
+		return errors.New("not a TCP connection")
 	}
 	if err := tcpConn.SetLinger(0); err != nil {
 		return err
diff --git a/cmd/syncthing/cli/client.go b/cmd/syncthing/cli/client.go
index 75923b421..7e0d8749e 100644
--- a/cmd/syncthing/cli/client.go
+++ b/cmd/syncthing/cli/client.go
@@ -91,11 +91,11 @@ func loadGUIConfig() (config.GUIConfiguration, error) {
 	guiCfg := cfg.GUI()
 
 	if guiCfg.Address() == "" {
-		return config.GUIConfiguration{}, errors.New("Could not find GUI Address")
+		return config.GUIConfiguration{}, errors.New("could not find GUI Address")
 	}
 
 	if guiCfg.APIKey == "" {
-		return config.GUIConfiguration{}, errors.New("Could not find GUI API key")
+		return config.GUIConfiguration{}, errors.New("could not find GUI API key")
 	}
 
 	return guiCfg, nil
diff --git a/lib/upgrade/upgrade_supported.go b/lib/upgrade/upgrade_supported.go
index bdea9e59d..6fb8e43f4 100644
--- a/lib/upgrade/upgrade_supported.go
+++ b/lib/upgrade/upgrade_supported.go
@@ -254,15 +254,9 @@ func readTarGz(archiveName, dir string, r io.Reader) (string, error) {
 	var sig []byte
 
 	// Iterate through the files in the archive.
-	i := 0
-	for {
-		if i >= maxArchiveMembers {
-			break
-		}
-		i++
-
+	for range maxArchiveMembers {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			// end of tar archive
 			break
 		}