diff --git a/src/ap/drv_callbacks.c b/src/ap/drv_callbacks.c
index 8d24e087e..4c0d0abac 100644
--- a/src/ap/drv_callbacks.c
+++ b/src/ap/drv_callbacks.c
@@ -86,8 +86,11 @@ int hostapd_notif_assoc(struct hostapd_data *hapd, const u8 *addr,
 		sta->timeout_next = STA_NULLFUNC;
 	} else {
 		sta = ap_sta_add(hapd, addr);
-		if (sta == NULL)
+		if (sta == NULL) {
+			hostapd_drv_sta_disassoc(hapd, addr,
+						 WLAN_REASON_DISASSOC_AP_BUSY);
 			return -1;
+		}
 	}
 	sta->flags &= ~(WLAN_STA_WPS | WLAN_STA_MAYBE_WPS | WLAN_STA_WPS2);