diff --git a/src/plugin/customParseFormat/index.js b/src/plugin/customParseFormat/index.js
index c7082833c..c6399a4e7 100644
--- a/src/plugin/customParseFormat/index.js
+++ b/src/plugin/customParseFormat/index.js
@@ -105,19 +105,19 @@ const expressions = {
   MMM: [matchWord, function (input) {
     const months = getLocalePart('months')
     const monthsShort = getLocalePart('monthsShort')
-    const matchIndex = (monthsShort || months.map(_ => _.slice(0, 3))).indexOf(input) + 1
-    if (matchIndex < 1) {
+    const matchIndex = (monthsShort || months.map(_ => _.slice(0, 3))).indexOf(input)
+    if (matchIndex < 0) {
       throw new Error()
     }
-    this.month = (matchIndex % 12) || matchIndex
+    this.month = (matchIndex % 12) + 1
   }],
   MMMM: [matchWord, function (input) {
     const months = getLocalePart('months')
-    const matchIndex = months.indexOf(input) + 1
-    if (matchIndex < 1) {
+    const matchIndex = months.indexOf(input)
+    if (matchIndex < 0) {
       throw new Error()
     }
-    this.month = (matchIndex % 12) || matchIndex
+    this.month = (matchIndex % 12) + 1
   }],
   Y: [matchSigned, addInput('year')],
   YY: [match2, function (input) {
diff --git a/test/plugin/customParseFormat.test.js b/test/plugin/customParseFormat.test.js
index fb4030176..ede745e31 100644
--- a/test/plugin/customParseFormat.test.js
+++ b/test/plugin/customParseFormat.test.js
@@ -1,6 +1,7 @@
 import MockDate from 'mockdate'
 import moment from 'moment'
 import dayjs from '../../src'
+import '../../src/locale/be'
 import '../../src/locale/ru'
 import uk from '../../src/locale/uk'
 import '../../src/locale/zh-cn'
@@ -211,6 +212,12 @@ it('parse month from short string with locale in argument', () => {
   expect(dayjs(input, format, 'uk').valueOf()).toBe(moment(input, format, 'uk').valueOf())
 })
 
+it('parse last month of year from short format string with locale', () => {
+  const input = '2018 снеж. 03'
+  const format = 'YYYY MMM DD'
+  expect(dayjs(input, format, 'be').valueOf()).toBe(moment(input, format, 'be').valueOf())
+})
+
 it('parse month from string with locale in argument', () => {
   const input = '2018 лютий 03'
   const format = 'YYYY MMMM DD'
@@ -218,6 +225,13 @@ it('parse month from string with locale in argument', () => {
   expect(dayjs(input, format, 'uk').valueOf()).toBe(moment(input, format, 'uk').valueOf())
 })
 
+it('parse last month of year from format string with locale', () => {
+  const input = '2018 грудня 03'
+  const format = 'YYYY MMMM DD'
+
+  expect(dayjs(input, format, 'uk').valueOf()).toBe(moment(input, format, 'uk').valueOf())
+})
+
 it('return Invalid Date when parse corrupt string', () => {
   const input = '2018 Turnip 03'
   const format = 'YYYY MMMM DD'