diff --git a/tests/codec-regression.sh b/tests/codec-regression.sh
index c7dea4c6ed..ba4a5a1b40 100755
--- a/tests/codec-regression.sh
+++ b/tests/codec-regression.sh
@@ -332,7 +332,7 @@ fi
 if [ -n "$do_zmbv" ] ; then
 # default level of 9 leads to different results with
 # different zlib versions
-do_video_encoding zmbv.avi "-an -vcodec zmbv -compression_level 6"
+do_video_encoding zmbv.avi "-an -vcodec zmbv -compression_level 0"
 do_video_decoding "" "-pix_fmt yuv420p"
 fi
 
diff --git a/tests/ref/vsynth1/zmbv b/tests/ref/vsynth1/zmbv
index 1413cad8e5..1175038bec 100644
--- a/tests/ref/vsynth1/zmbv
+++ b/tests/ref/vsynth1/zmbv
@@ -1,4 +1,4 @@
-ed417ff88cc5d8fe204b3dcc0ba71a57 *./tests/data/vsynth1/zmbv.avi
-2325956 ./tests/data/vsynth1/zmbv.avi
+796787e4dfb20762a1a66b1b395f85aa *./tests/data/vsynth1/zmbv.avi
+5112508 ./tests/data/vsynth1/zmbv.avi
 cfbec364e41d70c9b177435b5655d8af *./tests/data/zmbv.vsynth1.out.yuv
 stddev:   46.47 PSNR: 14.79 MAXDIFF:  129 bytes:  7603200/  7603200
diff --git a/tests/ref/vsynth2/zmbv b/tests/ref/vsynth2/zmbv
index b5fc304a3a..8aec802449 100644
--- a/tests/ref/vsynth2/zmbv
+++ b/tests/ref/vsynth2/zmbv
@@ -1,4 +1,4 @@
-71e6c69ab93b2b71736f71948032c9c4 *./tests/data/vsynth2/zmbv.avi
-1864098 ./tests/data/vsynth2/zmbv.avi
+a39f65c7075485235636343ef7217325 *./tests/data/vsynth2/zmbv.avi
+5116352 ./tests/data/vsynth2/zmbv.avi
 cfbec364e41d70c9b177435b5655d8af *./tests/data/zmbv.vsynth2.out.yuv
 stddev:   42.07 PSNR: 15.65 MAXDIFF:  112 bytes:  7603200/  7603200