diff --git a/intl/chardet/src/moz.build b/intl/chardet/src/moz.build
index 5cab4ab32d807..92179e3357820 100644
--- a/intl/chardet/src/moz.build
+++ b/intl/chardet/src/moz.build
@@ -4,7 +4,7 @@
 # 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/.
 
-SOURCES += [
+UNIFIED_SOURCES += [
     'nsChardetModule.cpp',
     'nsCyrillicDetector.cpp',
 ]