diff --git a/package.json b/package.json
index 3a45edc..bcaf47a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "react-intl-gettext",
-  "version": "5.0.1",
+  "version": "5.1.0",
   "description": "utilities to integrate react-intl with gettext",
   "main": "dist/index.js",
   "scripts": {
diff --git a/src/cli.js b/src/cli.js
index afc6604..6597188 100755
--- a/src/cli.js
+++ b/src/cli.js
@@ -5,7 +5,10 @@ import program from 'commander'
 import headerFormatter from './json2po/headerFormatter'
 import potFormatter from './json2po/potFormatter'
 import messageReader from './json2po/jsonMessageReader'
-import poMessageReader from './po2json/poMessageReader'
+import poMessageReader, {
+  defaultPattern,
+  defaultNameMatcherPatternString,
+} from './po2json/poMessageReader'
 import {
   getUserPackageJson,
   buildVersionFromPackageJson,
@@ -61,24 +64,34 @@ program
 program
   .command('po2json <src> <dest>')
   .description('converts po files to json')
-  .option('-p, --pattern [pattern]', 'glob pattern used to find the src files [**/*.po]', '**/*.po')
+  .option(
+    '-p, --pattern [pattern]',
+    `glob pattern used to find the src files [${defaultPattern}]`,
+    defaultPattern
+  )
   .option('--pretty', 'pretty print json')
   .option(
     '-i, --ignore <patterns>',
     'add a pattern or an array of glob patterns to exclude matches',
     list
   )
-  .action((src, dest, { pattern, pretty, ignore }) => {
+  .option(
+    '--lang-matcher-pattern [lang-matcher-pattern]',
+    `pattern used to match the language from the file name [${defaultNameMatcherPatternString}]`,
+    defaultNameMatcherPatternString
+  )
+  .action((src, dest, { pattern, pretty, ignore, langMatcherPattern }) => {
     writeFileSync(
       dest,
       JSON.stringify(
         poMessageReader({
           cwd: src,
           messagesPattern: pattern,
+          langMatcherPattern,
           ignore,
         }),
         null,
-        pretty ? '\t' : undefined
+        pretty ? '  ' : undefined
       )
     )
   })
diff --git a/src/po2json/poMessageReader.js b/src/po2json/poMessageReader.js
index 25ad253..2890535 100644
--- a/src/po2json/poMessageReader.js
+++ b/src/po2json/poMessageReader.js
@@ -3,12 +3,16 @@ import { join } from 'path'
 import { readFileSync } from 'fs'
 import { po } from 'gettext-parser'
 
-const defaultNameMatcher = filename => filename.match(/.*[-](.*)\.po$/)[1]
+const newNameMatcher = regex => filename => filename.match(regex)[1]
+
+export const defaultNameMatcherPatternString = '.*-(.*)\\.po$'
+export const defaultPattern = '**/*.po'
 
 export default ({
-  messagesPattern = '**/*.po',
+  messagesPattern = defaultPattern,
   cwd = process.cwd(),
-  langMatcher = defaultNameMatcher,
+  langMatcherPattern = defaultNameMatcherPatternString,
+  langMatcher = newNameMatcher(langMatcherPattern),
   ignore,
 }) => {
   const translations = globSync(messagesPattern, { cwd, ignore }).map(filename => {