diff --git a/editor/spellchecker/nsIInlineSpellChecker.idl b/editor/spellchecker/nsIInlineSpellChecker.idl
index d6f1b897b226..b95bb954b4ae 100644
--- a/editor/spellchecker/nsIInlineSpellChecker.idl
+++ b/editor/spellchecker/nsIInlineSpellChecker.idl
@@ -31,7 +31,7 @@ interface nsIInlineSpellChecker : nsISupports
   void removeWordFromDictionary(in AString aWord);
 
   void ignoreWord(in AString aWord);
-  void ignoreWords([array, size_is(aCount)] in wstring aWordsToIgnore, in unsigned long aCount);
+  void ignoreWords(in Array<AString> aWordsToIgnore);
   void updateCurrentDictionary();
 
   readonly attribute boolean spellCheckPending;
diff --git a/extensions/spellcheck/src/mozInlineSpellChecker.cpp b/extensions/spellcheck/src/mozInlineSpellChecker.cpp
index 490e1121ab54..3df99ebeefe7 100644
--- a/extensions/spellcheck/src/mozInlineSpellChecker.cpp
+++ b/extensions/spellcheck/src/mozInlineSpellChecker.cpp
@@ -923,14 +923,13 @@ mozInlineSpellChecker::IgnoreWord(const nsAString& word) {
 // mozInlineSpellChecker::IgnoreWords
 
 NS_IMETHODIMP
-mozInlineSpellChecker::IgnoreWords(const char16_t** aWordsToIgnore,
-                                   uint32_t aCount) {
+mozInlineSpellChecker::IgnoreWords(const nsTArray<nsString>& aWordsToIgnore) {
   NS_ENSURE_TRUE(mSpellCheck, NS_ERROR_NOT_INITIALIZED);
 
   // add each word to the ignore list and then recheck the document
-  for (uint32_t index = 0; index < aCount; index++)
-    mSpellCheck->IgnoreWordAllOccurrences(
-        nsDependentString(aWordsToIgnore[index]));
+  for (auto& word : aWordsToIgnore) {
+    mSpellCheck->IgnoreWordAllOccurrences(word);
+  }
 
   auto status = MakeUnique<mozInlineSpellStatus>(this);
   nsresult rv = status->InitForSelection();