--- a/js/src/builtin/intl/Locale.cpp
+++ b/js/src/builtin/intl/Locale.cpp
@@ -796,18 +796,20 @@ static mozilla::Maybe<IndexAndLength> Fi
   return mozilla::Some(IndexAndLength{size_t(beginType - extension),
                                       size_t(endType - beginType)});
 }
 
 static inline auto FindUnicodeExtensionType(JSLinearString* unicodeExtension,
                                             UnicodeKey key) {
   JS::AutoCheckCannotGC nogc;
   return unicodeExtension->hasLatin1Chars()
-             ? FindUnicodeExtensionType(unicodeExtension->latin1Chars(nogc),
-                                        unicodeExtension->length(), key)
+             ? FindUnicodeExtensionType(
+                   reinterpret_cast<const char*>(
+                       unicodeExtension->latin1Chars(nogc)),
+                   unicodeExtension->length(), key)
              : FindUnicodeExtensionType(unicodeExtension->twoByteChars(nogc),
                                         unicodeExtension->length(), key);
 }
 
 // Return the sequence of types for the Unicode extension keyword specified by
 // key or undefined when the keyword isn't present.
 static bool GetUnicodeExtension(JSContext* cx, LocaleObject* locale,
                                 UnicodeKey key, MutableHandleValue value) {
@@ -914,17 +916,19 @@ static BaseNamePartsResult BaseNameParts
   }
 
   return {language, script, region};
 }
 
 static inline auto BaseNameParts(JSLinearString* baseName) {
   JS::AutoCheckCannotGC nogc;
   return baseName->hasLatin1Chars()
-             ? BaseNameParts(baseName->latin1Chars(nogc), baseName->length())
+             ? BaseNameParts(
+                   reinterpret_cast<const char*>(baseName->latin1Chars(nogc)),
+                   baseName->length())
              : BaseNameParts(baseName->twoByteChars(nogc), baseName->length());
 }
 
 // Intl.Locale.prototype.maximize ()
 static bool Locale_maximize(JSContext* cx, const CallArgs& args) {
   MOZ_ASSERT(IsLocale(args.thisv()));
 
   // Step 3.