diff --git a/src/modules/topos/topos_mod.c b/src/modules/topos/topos_mod.c
index fa70d06bb92..d698b90cc12 100644
--- a/src/modules/topos/topos_mod.c
+++ b/src/modules/topos/topos_mod.c
@@ -269,8 +269,13 @@ int tps_prepare_msg(sip_msg_t *msg)
 			LM_DBG("non sip request message\n");
 			return 1;
 		}
-	} else if(msg->first_line.type!=SIP_REPLY) {
-		LM_DBG("non sip message\n");
+	} else if(msg->first_line.type==SIP_REPLY) {
+		if(!IS_SIP_REPLY(msg)) {
+			LM_DBG("non sip reply message\n");
+			return 1;
+		}
+	} else {
+		LM_DBG("unknown sip message type %d\n", msg->first_line.type);
 		return 1;
 	}