diff --git a/src/ap/hw_features.h b/src/ap/hw_features.h
index 902a19f9f..67493193a 100644
--- a/src/ap/hw_features.h
+++ b/src/ap/hw_features.h
@@ -49,7 +49,7 @@ static inline int hostapd_select_hw_mode(struct hostapd_iface *iface)
 
 static inline const char * hostapd_hw_mode_txt(int mode)
 {
-	return NULL;
+	return "UNKNOWN";
 }
 
 static inline int hostapd_hw_get_freq(struct hostapd_data *hapd, int chan)