diff --git a/resources/assets/js/components/NewInvoice.vue b/resources/assets/js/components/NewInvoice.vue
index b6d5b3c4..b0b1c5d8 100644
--- a/resources/assets/js/components/NewInvoice.vue
+++ b/resources/assets/js/components/NewInvoice.vue
@@ -671,10 +671,16 @@ export default {
       this.clearAddLine()
     },
     onUnitPriceRMB: function () {
+      if (!this.form.addLine.unit_price_rmb) {
+        return
+      }
       this.form.addLine.unit_price_rm = (+this.form.addLine.unit_price_rmb / +this.rate).toFixed(2)
       this.form.addLine.total = (+this.form.addLine.unit_price_rm * +this.form.addLine.quantity).toFixed(2)
     },
     onUnitPriceRM: function () {
+      if (!this.form.addLine.unit_price_rm) {
+        return
+      }
       this.form.addLine.unit_price_rmb = (this.form.addLine.unit_price_rm * this.rate).toFixed(2)
       this.form.addLine.total = (+this.form.addLine.unit_price_rm * +this.form.addLine.quantity).toFixed(2)
     },