--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -333,14 +333,9 @@ include('/ipc/chromium/chromium-config.m
 #  - about attributes on forward declarations for types that are already
 #    defined, which complains about an important MOZ_EXPORT for android::AString
 if CONFIG['GNU_CC']:
     CXXFLAGS += [
         '-Wno-error=attributes',
         '-Wno-error=shadow',
     ]
 
-if CONFIG['_MSC_VER']:
-    # This is intended as a temporary workaround to unblock compilation
-    # on VS2015 in warnings as errors mode.
-    CXXFLAGS += ['-wd4312']
-
 FINAL_LIBRARY = 'xul'