diff --git a/wpa_supplicant/config.c b/wpa_supplicant/config.c
index da9580e94..23aab4ba9 100644
--- a/wpa_supplicant/config.c
+++ b/wpa_supplicant/config.c
@@ -438,10 +438,10 @@ static char * wpa_config_write_proto(const struct parse_data *data,
 	int first = 1, ret;
 	char *buf, *pos, *end;
 
-	pos = buf = os_zalloc(10);
+	pos = buf = os_zalloc(20);
 	if (buf == NULL)
 		return NULL;
-	end = buf + 10;
+	end = buf + 20;
 
 	if (ssid->proto & WPA_PROTO_WPA) {
 		ret = os_snprintf(pos, end - pos, "%sWPA", first ? "" : " ");
@@ -459,6 +459,14 @@ static char * wpa_config_write_proto(const struct parse_data *data,
 		first = 0;
 	}
 
+	if (ssid->proto & WPA_PROTO_OSEN) {
+		ret = os_snprintf(pos, end - pos, "%sOSEN", first ? "" : " ");
+		if (ret < 0 || ret >= end - pos)
+			return buf;
+		pos += ret;
+		first = 0;
+	}
+
 	return buf;
 }
 #endif /* NO_CONFIG_WRITE */