diff --git a/src/constant.js b/src/constant.js
index 52547342e..25ab6170e 100644
--- a/src/constant.js
+++ b/src/constant.js
@@ -26,5 +26,5 @@ export const FORMAT_DEFAULT = 'YYYY-MM-DDTHH:mm:ssZ'
 export const INVALID_DATE_STRING = 'Invalid Date'
 
 // regex
-export const REGEX_PARSE = /^(\d{4})[-/]?(\d{1,2})?[-/]?(\d{0,2})[Tt\s]*(\d{1,2})?:?(\d{1,2})?:?(\d{1,2})?[.:]?(\d+)?$/
+export const REGEX_PARSE = /^(?!\d{9,}$)(\d{4})[-/]?(\d{1,2})?[-/]?(\d{0,2})[Tt\s]*(\d{1,2})?:?(\d{1,2})?:?(\d{1,2})?[.:]?(\d+)?$/
 export const REGEX_FORMAT = /\[([^\]]+)]|YYYY|YY|M{1,4}|D{1,2}|d{1,4}|H{1,2}|h{1,2}|a|A|m{1,2}|s{1,2}|Z{1,2}|SSS/g
diff --git a/test/parse.test.js b/test/parse.test.js
index 9f2dedf2d..6d7406e33 100644
--- a/test/parse.test.js
+++ b/test/parse.test.js
@@ -213,3 +213,18 @@ describe('REGEX_PARSE', () => {
     expect(d).toBe(null)
   })
 })
+
+describe('Timestamp string', () => {
+  // #2955
+  it('timestamp passed as string is invalid', () => {
+    expect(dayjs('1762232987879').isValid()).toBe(false)
+    expect(dayjs('1581314281').isValid()).toBe(false)
+    expect(dayjs('123456789').isValid()).toBe(false)
+  })
+  it('digit-only date formats still parse', () => {
+    expect(dayjs('2018').year()).toBe(2018)
+    expect(dayjs('201805').format('YYYY-MM')).toBe('2018-05')
+    expect(dayjs('20180517').format('YYYY-MM-DD')).toBe('2018-05-17')
+    expect(dayjs('20210102T012345').isValid()).toBe(true)
+  })
+})