diff --git a/iwinfo_cli.c b/iwinfo_cli.c
index 35cc380..c052d63 100644
--- a/iwinfo_cli.c
+++ b/iwinfo_cli.c
@@ -58,7 +58,7 @@ static char * format_channel(int ch)
 
 static char * format_frequency(int freq)
 {
-	static char buf[10];
+	static char buf[11];
 
 	if (freq <= 0)
 		snprintf(buf, sizeof(buf), "unknown");