diff --git a/libavformat/md5enc.c b/libavformat/md5enc.c
index dc8919a8c8..4509c18e84 100644
--- a/libavformat/md5enc.c
+++ b/libavformat/md5enc.c
@@ -75,6 +75,7 @@ AVOutputFormat ff_md5_muxer = {
     .write_header      = write_header,
     .write_packet      = write_packet,
     .write_trailer     = write_trailer,
+    .flags             = AVFMT_NOTIMESTAMPS,
 };
 #endif
 
@@ -102,5 +103,6 @@ AVOutputFormat ff_framemd5_muxer = {
     .audio_codec       = CODEC_ID_PCM_S16LE,
     .video_codec       = CODEC_ID_RAWVIDEO,
     .write_packet      = framemd5_write_packet,
+    .flags             = AVFMT_VARIABLE_FPS,
 };
 #endif
diff --git a/tests/fate/vp8.mak b/tests/fate/vp8.mak
index 1f442af4ac..be8f50aaf8 100644
--- a/tests/fate/vp8.mak
+++ b/tests/fate/vp8.mak
@@ -10,7 +10,7 @@ define FATE_VP8_FULL
 $(foreach N,$(VP8_SUITE),$(eval $(call FATE_VP8_SUITE,$(N),$(1),$(2))))
 
 FATE_VP8 += fate-vp8-sign-bias$(1)
-fate-vp8-sign-bias$(1): CMD = framemd5 $(2) -i $(SAMPLES)/vp8/sintel-signbias.ivf
+fate-vp8-sign-bias$(1): CMD = framemd5 $(2) -i $(SAMPLES)/vp8/sintel-signbias.ivf -vsync 0
 fate-vp8-sign-bias$(1): REF = $(SRC_PATH)/tests/ref/fate/vp8-sign-bias
 endef