diff --git a/packages/cli/src/api/formats/__snapshots__/po-gettext.test.ts.snap b/packages/cli/src/api/formats/__snapshots__/po-gettext.test.ts.snap
index dff78d61d..6bf3d0541 100644
--- a/packages/cli/src/api/formats/__snapshots__/po-gettext.test.ts.snap
+++ b/packages/cli/src/api/formats/__snapshots__/po-gettext.test.ts.snap
@@ -1,5 +1,44 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[` 1`] = `
+Object {
+  message_with_id: Object {
+    comments: Array [],
+    extractedComments: Array [],
+    flags: Array [],
+    obsolete: false,
+    origin: Array [],
+    translation: {someCount, plural, one {Singular case} other {Case number {someCount}}},
+  },
+  message_with_id_but_without_translation: Object {
+    comments: Array [],
+    extractedComments: Array [
+      Comment made by the developers.,
+    ],
+    flags: Array [],
+    obsolete: false,
+    origin: Array [],
+    translation: ,
+  },
+  {anotherCount, plural, one {Singular case} other {Case number {anotherCount}}}: Object {
+    comments: Array [],
+    extractedComments: Array [],
+    flags: Array [],
+    obsolete: false,
+    origin: Array [],
+    translation: {anotherCount, plural, one {Singular case} other {Case number {anotherCount}}},
+  },
+  {count, plural, one {Singular} other {Plural}}: Object {
+    comments: Array [],
+    extractedComments: Array [],
+    flags: Array [],
+    obsolete: false,
+    origin: Array [],
+    translation: ,
+  },
+}
+`;
+
 exports[`po-gettext format should convert ICU plural messages to gettext plurals 1`] = `
 msgid ""
 msgstr ""
diff --git a/packages/cli/src/api/formats/fixtures/messages_plural-4-letter.po b/packages/cli/src/api/formats/fixtures/messages_plural-4-letter.po
new file mode 100644
index 000000000..c318bb849
--- /dev/null
+++ b/packages/cli/src/api/formats/fixtures/messages_plural-4-letter.po
@@ -0,0 +1,33 @@
+msgid ""
+msgstr ""
+"POT-Creation-Date: 2018-08-27 10:00+0000\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=utf-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: @lingui/cli\n"
+"Language: en_CA\n"
+
+#. js-lingui:pluralize_on=someCount
+msgid "message_with_id"
+msgid_plural "message_with_id_plural"
+msgstr[0] "Singular case"
+msgstr[1] "Case number {someCount}"
+
+#. js-lingui:icu=%7BanotherCount%2C+plural%2C+one+%7BSingular+case%7D+other+%7BCase+number+%7BanotherCount%7D%7D%7D&pluralize_on=anotherCount
+msgid "Singular case"
+msgid_plural "Case number {anotherCount}"
+msgstr[0] "Singular case"
+msgstr[1] "Case number {anotherCount}"
+
+#. Comment made by the developers.
+#. js-lingui:pluralize_on=count
+msgid "message_with_id_but_without_translation"
+msgid_plural "message_with_id_but_without_translation_plural"
+msgstr[0] ""
+msgstr[1] ""
+
+#. js-lingui:icu=%7Bcount%2C+plural%2C+one+%7BSingular%7D+other+%7BPlural%7D%7D&pluralize_on=count
+msgid "Singular"
+msgid_plural "Plural"
+msgstr[0] ""
+msgstr[1] ""
\ No newline at end of file
diff --git a/packages/cli/src/api/formats/po-gettext.test.ts b/packages/cli/src/api/formats/po-gettext.test.ts
index 1489b9e3f..82e707521 100644
--- a/packages/cli/src/api/formats/po-gettext.test.ts
+++ b/packages/cli/src/api/formats/po-gettext.test.ts
@@ -366,4 +366,15 @@ msgstr[2] "# dní"
       })
     })
   })
+
+  describe("convertPluralsToIco handle correctly locales with 4-letter", () => {
+    const pofile = fs
+    .readFileSync(
+      path.join(path.resolve(__dirname), "fixtures", "messages_plural-4-letter.po")
+    )
+    .toString()
+
+  const catalog = format.parse(pofile)
+  expect(catalog).toMatchSnapshot()
+  })
 })
diff --git a/packages/cli/src/api/formats/po-gettext.ts b/packages/cli/src/api/formats/po-gettext.ts
index 7b86aa37e..d041b7779 100644
--- a/packages/cli/src/api/formats/po-gettext.ts
+++ b/packages/cli/src/api/formats/po-gettext.ts
@@ -204,10 +204,12 @@ const deserialize: (Object) => Object = R.map(
  * https://github.com/LLK/po2icu/blob/9eb97f81f72b2fee02b77f1424702e019647e9b9/lib/po2icu.js#L148.
  */
 const getPluralCases = (lang: string): string[] | undefined => {
-  const gettextPluralsInfo = gettextPlurals[lang]
+  // If users uses locale with underscore or slash, es-ES, es_ES, gettextplural is "es" not es-ES.
+  const [correctLang] = lang.split(/[-_]/g)
+  const gettextPluralsInfo = gettextPlurals[correctLang]
 
   return gettextPluralsInfo?.examples.map((pluralCase) =>
-    pluralsCldr(lang, pluralCase.sample)
+    pluralsCldr(correctLang, pluralCase.sample)
   )
 }