diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index 34ec2b3e61..1771e71d06 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -2653,10 +2653,9 @@ int ff_mpeg4_frame_end(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
         }
 
         if (startcode_found) {
-            av_fast_malloc(&s->bitstream_buffer,
+            av_fast_padded_malloc(&s->bitstream_buffer,
                            &s->allocated_bitstream_buffer_size,
-                           buf_size - current_pos +
-                           FF_INPUT_BUFFER_PADDING_SIZE);
+                           buf_size - current_pos);
             if (!s->bitstream_buffer)
                 return AVERROR(ENOMEM);
             memcpy(s->bitstream_buffer, buf + current_pos,