diff --git a/libavfilter/buffer.c b/libavfilter/buffer.c
index c939388656..439425a3ee 100644
--- a/libavfilter/buffer.c
+++ b/libavfilter/buffer.c
@@ -146,7 +146,7 @@ int avfilter_copy_buf_props(AVFrame *dst, const AVFilterBufferRef *src)
             if (!dst->extended_data)
                 return AVERROR(ENOMEM);
             memcpy(dst->extended_data, src->extended_data,
-                   planes * sizeof(dst->extended_data));
+                   planes * sizeof(*dst->extended_data));
         } else
             dst->extended_data = dst->data;