diff --git a/editor/AsyncSpellCheckTestHelper.jsm b/editor/AsyncSpellCheckTestHelper.jsm
index 77bfee17b162..78d5f2993f8e 100644
--- a/editor/AsyncSpellCheckTestHelper.jsm
+++ b/editor/AsyncSpellCheckTestHelper.jsm
@@ -2,11 +2,19 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var EXPORTED_SYMBOLS = ["maybeOnSpellCheck", "onSpellCheck"];
+var EXPORTED_SYMBOLS = [
+  "maybeOnSpellCheck",
+  "onSpellCheck",
+  "getDictionaryContentPref",
+];
 
 const SPELL_CHECK_ENDED_TOPIC = "inlineSpellChecker-spellCheck-ended";
 const SPELL_CHECK_STARTED_TOPIC = "inlineSpellChecker-spellCheck-started";
 
+const CP = Cc["@mozilla.org/content-pref/service;1"].getService(
+  Ci.nsIContentPrefService2
+);
+
 /**
  * Waits until spell checking has stopped on the given element.
  *
@@ -105,3 +113,19 @@ function onSpellCheck(editableElement, callback) {
     callback
   );
 }
+
+async function getDictionaryContentPref() {
+  let dictionaries = await new Promise(resolve => {
+    let value = "";
+    CP.getByDomainAndName("mochi.test", "spellcheck.lang", null, {
+      handleResult(pref) {
+        value = pref.value;
+      },
+      handleCompletion() {
+        resolve(value);
+      },
+    });
+  });
+
+  return dictionaries;
+}
diff --git a/editor/spellchecker/EditorSpellCheck.cpp b/editor/spellchecker/EditorSpellCheck.cpp
index bf5cc7dbbaf6..77855dcd04eb 100644
--- a/editor/spellchecker/EditorSpellCheck.cpp
+++ b/editor/spellchecker/EditorSpellCheck.cpp
@@ -603,10 +603,9 @@ EditorSpellCheck::SetCurrentDictionaries(
     mEditor->GetFlags(&flags);
     if (!(flags & nsIEditor::eEditorMailMask)) {
       if (!aDictionaries.IsEmpty() &&
-          (mPreferredLang.IsEmpty() ||
-           (aDictionaries.Length() == 1 &&
-            !mPreferredLang.Equals(aDictionaries[0],
-                                   nsCaseInsensitiveCStringComparator)))) {
+          (mPreferredLang.IsEmpty() || aDictionaries.Length() > 1 ||
+           !mPreferredLang.Equals(aDictionaries[0],
+                                  nsCaseInsensitiveCStringComparator))) {
         // When user sets dictionary manually, we store this value associated
         // with editor url, if it doesn't match the document language exactly.
         // For example on "en" sites, we need to store "en-GB", otherwise
diff --git a/editor/spellchecker/tests/mochitest.ini b/editor/spellchecker/tests/mochitest.ini
index 448950c71cff..c7d611585855 100644
--- a/editor/spellchecker/tests/mochitest.ini
+++ b/editor/spellchecker/tests/mochitest.ini
@@ -41,6 +41,7 @@ skip-if = e10s
 [test_bug1418629.html]
 [test_bug1497480.html]
 [test_bug1602526.html]
+[test_bug1761273.html]
 [test_spellcheck_after_edit.html]
 [test_spellcheck_after_pressing_navigation_key.html]
 [test_suggest.html]
diff --git a/editor/spellchecker/tests/test_bug1402822.html b/editor/spellchecker/tests/test_bug1402822.html
index e091d9611f8d..ba43d49a82c1 100644
--- a/editor/spellchecker/tests/test_bug1402822.html
+++ b/editor/spellchecker/tests/test_bug1402822.html
@@ -4,13 +4,13 @@
 https://bugzilla.mozilla.org/show_bug.cgi?id=1402822
 -->
 <head>
-  <title>Test for Bug 1209414</title>
+  <title>Test for Bug 1402822</title>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
   <script src="/tests/SimpleTest/EventUtils.js"></script>
   <link rel="stylesheet" href="/tests/SimpleTest/test.css">
 </head>
 <body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1209414">Mozilla Bug 1209414</a>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1402822">Mozilla Bug 1402822</a>
 <p id="display"></p>
 </div>
 
diff --git a/editor/spellchecker/tests/test_bug1761273.html b/editor/spellchecker/tests/test_bug1761273.html
new file mode 100644
index 000000000000..a1e01fbdba25
--- /dev/null
+++ b/editor/spellchecker/tests/test_bug1761273.html
@@ -0,0 +1,92 @@
+<!DOCTYPE html>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1761273
+-->
+<head>
+  <title>Test for Bug 1761273</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1761273">Mozilla Bug 1761273</a>
+<p id="display"></p>
+</div>
+
+<textarea id="editor" lang="en-US">heute ist ein guter Tag - today is a good day</textarea>
+
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+const Ci = SpecialPowers.Ci;
+
+let {getDictionaryContentPref, onSpellCheck} = SpecialPowers.Cu.import("resource://testing-common/AsyncSpellCheckTestHelper.jsm", {});
+
+/** Test for Bug 1402822 **/
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(start);
+async function start() {
+  /* global actorParent */
+  /* eslint-env mozilla/frame-script */
+  let script = SpecialPowers.loadChromeScript(() => {
+    // eslint-disable-next-line mozilla/use-services
+    let dir = Cc["@mozilla.org/file/directory_service;1"]
+                .getService(Ci.nsIProperties)
+                .get("CurWorkD", Ci.nsIFile);
+    dir.append("tests");
+    dir.append("editor");
+    dir.append("spellchecker");
+    dir.append("tests");
+
+    let hunspell = Cc["@mozilla.org/spellchecker/engine;1"]
+                     .getService(Ci.mozISpellCheckingEngine);
+
+    // Install de-DE dictionary.
+    let de_DE = dir.clone();
+    de_DE.append("de-DE");
+    hunspell.addDirectory(de_DE);
+
+    addMessageListener("destroy", () => hunspell.removeDirectory(de_DE));
+    addMessageListener("de_DE-exists", () => de_DE.exists());
+  });
+  is(await script.sendQuery("de_DE-exists"), true,
+     "true expected (de_DE directory should exist)");
+
+  let textarea = document.getElementById("editor");
+  textarea.focus();
+
+  onSpellCheck(textarea, async () => {
+    let isc = SpecialPowers.wrap(textarea).editor.getInlineSpellChecker(true);
+    ok(isc, "Inline spell checker should exist after focus and spell check");
+    let spellchecker = isc.spellChecker;
+
+    // Setting the language to the language of the texteditor should not set the
+    // content preference.
+    await spellchecker.setCurrentDictionaries(["en-US"]);
+    let dictionaryContentPref = await getDictionaryContentPref();
+    is(dictionaryContentPref, "", "Content pref should be empty");
+
+    await spellchecker.setCurrentDictionaries(["en-US", "de-DE"]);
+    dictionaryContentPref = await getDictionaryContentPref();
+    is(dictionaryContentPref, "en-US,de-DE,", "Content pref should be en-US,de-DE,");
+
+    await spellchecker.setCurrentDictionaries(["de-DE"]);
+    dictionaryContentPref = await getDictionaryContentPref();
+    is(dictionaryContentPref, "de-DE,", "Content pref should be de-DE,");
+
+    // Remove the fake de_DE dictionary again.
+    await script.sendQuery("destroy");
+
+    // This will clear the content preferences and reset "spellchecker.dictionary".
+    await spellchecker.setCurrentDictionaries([]);
+    dictionaryContentPref = await getDictionaryContentPref();
+    is(dictionaryContentPref, "", "Content pref should be empty");
+
+    SimpleTest.finish();
+  });
+}
+</script>
+</pre>
+</body>
+</html>
