diff --git a/tests/regression-funcs.sh b/tests/regression-funcs.sh
index b79c258e77..933aa648d6 100755
--- a/tests/regression-funcs.sh
+++ b/tests/regression-funcs.sh
@@ -53,7 +53,7 @@ echov(){
 FFMPEG_OPTS="-v 0 -y"
 COMMON_OPTS="-flags +bitexact -idct simple -sws_flags +accurate_rnd+bitexact"
 DEC_OPTS="$COMMON_OPTS -threads $threads"
-ENC_OPTS="$COMMON_OPTS -dct fastint"
+ENC_OPTS="$COMMON_OPTS -threads 1 -dct fastint"
 
 run_ffmpeg()
 {