diff --git a/slstatus.c b/slstatus.c
index 4b69cc6..c56efd9 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -658,7 +658,7 @@ wifi_perc(const char *wificard)
 
 /* main function */
 int
-main()
+main(void)
 {
     char status_string[1024];
     struct arg argument;