diff --git a/libavfilter/af_stereowiden.c b/libavfilter/af_stereowiden.c
index af4b23e8a5..97610a4f30 100644
--- a/libavfilter/af_stereowiden.c
+++ b/libavfilter/af_stereowiden.c
@@ -72,7 +72,7 @@ static int config_input(AVFilterLink *inlink)
     AVFilterContext *ctx = inlink->dst;
     StereoWidenContext *s = ctx->priv;
 
-    s->length = s->delay * inlink->sample_rate / 1000;
+    s->length = lrintf(s->delay * inlink->sample_rate / 1000);
     s->length *= 2;
     s->buffer = av_calloc(s->length, sizeof(*s->buffer));
     if (!s->buffer)