diff --git a/media/ffvpx/libavcodec/moz.build b/media/ffvpx/libavcodec/moz.build
index 0069865..e806fc8 100644
--- a/media/ffvpx/libavcodec/moz.build
+++ b/media/ffvpx/libavcodec/moz.build
@@ -112,9 +112,15 @@ if not CONFIG['MOZ_FFVPX_AUDIOONLY']:
             'vaapi_vp8.c',
             'vaapi_vp9.c',
         ]
+        if CONFIG["MOZ_SYSTEM_AV1"]:
+          CFLAGS += CONFIG['MOZ_SYSTEM_LIBDAV1D_CFLAGS']
+          OS_LIBS += CONFIG['MOZ_SYSTEM_LIBDAV1D_LIBS']
+        else:
+          USE_LIBS += [
+            'dav1d',
+            'media_libdav1d_asm',
+          ]
         USE_LIBS += [
-          'dav1d',
-          'media_libdav1d_asm',
           'mozva'
         ]