diff --git a/src/index.js b/src/index.js
index 8c8841a81..347c08de2 100644
--- a/src/index.js
+++ b/src/index.js
@@ -243,7 +243,7 @@ class Dayjs {
     const unit = Utils.p(units)
     const instanceFactorySet = (n) => {
       const date = new Date(this.$d)
-      date.setDate(date.getDate() + (n * number))
+      date.setDate(date.getDate() + Math.round(n * number))
       return Utils.w(date, this)
     }
     if (unit === C.M) {
diff --git a/test/manipulate.test.js b/test/manipulate.test.js
index eb83f5d92..5fe28cb4f 100644
--- a/test/manipulate.test.js
+++ b/test/manipulate.test.js
@@ -64,6 +64,13 @@ it('Add Time days', () => {
   expect(dayjs().add('2', 'years').valueOf()).toBe(moment().add('2', 'years').valueOf())
 })
 
+it('Add Time with decimal', () => {
+  expect(dayjs().add(0.4, 'day').valueOf()).toBe(moment().add(0.4, 'day').valueOf())
+  expect(dayjs().add(0.5, 'day').valueOf()).toBe(moment().add(0.5, 'day').valueOf())
+  expect(dayjs().add(0.4, 'week').valueOf()).toBe(moment().add(0.4, 'week').valueOf())
+  expect(dayjs().add(0.5, 'week').valueOf()).toBe(moment().add(0.5, 'week').valueOf())
+})
+
 it('Subtract Time days', () => {
   expect(dayjs().subtract(1, 'days').valueOf()).toBe(moment().subtract(1, 'days').valueOf())
 })