diff --git a/slog.go b/slog.go
index 18e43e7..603123c 100644
--- a/slog.go
+++ b/slog.go
@@ -79,7 +79,7 @@ func NewSLogger() (ret *SLogger) {
 	ret.verbose = false
 	ret.timeformat = "2006-01-02 15:04:05 MST"
 	ret.formatfct = defaultSLogFormatFct
-	ret.loggers = []io.Writer{NewStdoutLogger()}
+	ret.loggers = []io.WriteCloser{NewStdoutLogger()}
 
 	return ret
 }
@@ -177,11 +177,11 @@ func SET_TIMEFORMAT(timeformat string) {
 	defaultSLog.SetTimeFormat(timeformat)
 }
 
-func ADD_LOGGER(logger io.Writer) {
+func ADD_LOGGER(logger io.WriteCloser) {
 	defaultSLog.AddLogger(logger)
 }
 
-func SET_LOGGERS(loggers []io.Writer) {
+func SET_LOGGERS(loggers []io.WriteCloser) {
 	defaultSLog.SetLoggers(loggers)
 }
 
@@ -209,11 +209,11 @@ func (sl *SLogger) SetTimeFormat(format string) {
 	sl.timeformat = format
 }
 
-func (sl *SLogger) AddLogger(logger io.Writer) {
+func (sl *SLogger) AddLogger(logger io.WriteCloser) {
 	sl.loggers = append(sl.loggers, logger)
 }
 
-func (sl *SLogger) SetLoggers(loggers []io.Writer) {
+func (sl *SLogger) SetLoggers(loggers []io.WriteCloser) {
 	sl.loggers = loggers
 }