diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index 1904a1c625..a806c38a6f 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -407,7 +407,7 @@ static void decode_ac_filter(WmallDecodeCtx *s)
     s->acfilter_scaling = get_bits(&s->gb, 4);
 
     for (i = 0; i < s->acfilter_order; i++)
-        s->acfilter_coeffs[i] = get_bits(&s->gb, s->acfilter_scaling) + 1;
+        s->acfilter_coeffs[i] = (s->acfilter_scaling ? get_bits(&s->gb, s->acfilter_scaling) : 0) + 1;
 }
 
 static void decode_mclms(WmallDecodeCtx *s)