diff --git a/src/index.js b/src/index.js
index 061ade178..3d2d0107a 100644
--- a/src/index.js
+++ b/src/index.js
@@ -357,13 +357,13 @@ class Dayjs {
     let result
     switch (unit) {
       case C.Y:
-        result = getMonth() / 12
+        result = (getMonth() / 12) || diff
         break
       case C.M:
-        result = getMonth()
+        result = getMonth() || diff
         break
       case C.Q:
-        result = getMonth() / 3
+        result = (getMonth() / 3) || diff
         break
       case C.W:
         result = (diff - zoneDelta) / C.MILLISECONDS_A_WEEK
diff --git a/test/issues/issue2793.diff.test.js b/test/issues/issue2793.diff.test.js
new file mode 100644
index 000000000..2b3d38034
--- /dev/null
+++ b/test/issues/issue2793.diff.test.js
@@ -0,0 +1,12 @@
+import dayjs from '../../src'
+
+describe('issue 2793 - diff with invalid date should return NaN', () => {
+  ['days', 'week', 'month', 'quarter', 'year', 'hour', 'minute', 'second'].forEach((unit) => {
+    it(`should return NaN for ${unit}`, () => {
+      const currentDate = dayjs()
+      const expiresOn = dayjs(null)
+      const diffDays = expiresOn.diff(currentDate, unit)
+      expect(diffDays).toBeNaN()
+    })
+  })
+})