diff --git a/libavcodec/mjpegenc.c b/libavcodec/mjpegenc.c
index d4db8d83da..1129118856 100644
--- a/libavcodec/mjpegenc.c
+++ b/libavcodec/mjpegenc.c
@@ -159,13 +159,12 @@ static void jpeg_table_header(MpegEncContext *s)
     AV_WB16(ptr, size);
 }
 
-static void jpeg_put_comments(MpegEncContext *s)
+static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p)
 {
-    PutBitContext *p = &s->pb;
     int size;
     uint8_t *ptr;
 
-    if (s->avctx->sample_aspect_ratio.num /* && !lossless */)
+    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0)
     {
     /* JFIF header */
     put_marker(p, APP0);
@@ -173,14 +172,14 @@ static void jpeg_put_comments(MpegEncContext *s)
     avpriv_put_string(p, "JFIF", 1); /* this puts the trailing zero-byte too */
     put_bits(p, 16, 0x0102); /* v 1.02 */
     put_bits(p, 8, 0); /* units type: 0 - aspect ratio */
-    put_bits(p, 16, s->avctx->sample_aspect_ratio.num);
-    put_bits(p, 16, s->avctx->sample_aspect_ratio.den);
+    put_bits(p, 16, avctx->sample_aspect_ratio.num);
+    put_bits(p, 16, avctx->sample_aspect_ratio.den);
     put_bits(p, 8, 0); /* thumbnail width */
     put_bits(p, 8, 0); /* thumbnail height */
     }
 
     /* comment */
-    if(!(s->flags & CODEC_FLAG_BITEXACT)){
+    if (!(avctx->flags & CODEC_FLAG_BITEXACT)) {
         put_marker(p, COM);
         flush_put_bits(p);
         ptr = put_bits_ptr(p);
@@ -190,9 +189,9 @@ static void jpeg_put_comments(MpegEncContext *s)
         AV_WB16(ptr, size);
     }
 
-    if(  s->avctx->pix_fmt == AV_PIX_FMT_YUV420P
-       ||s->avctx->pix_fmt == AV_PIX_FMT_YUV422P
-       ||s->avctx->pix_fmt == AV_PIX_FMT_YUV444P){
+    if(  avctx->pix_fmt == AV_PIX_FMT_YUV420P
+       ||avctx->pix_fmt == AV_PIX_FMT_YUV422P
+       ||avctx->pix_fmt == AV_PIX_FMT_YUV444P){
         put_marker(p, COM);
         flush_put_bits(p);
         ptr = put_bits_ptr(p);
@@ -213,7 +212,7 @@ void ff_mjpeg_encode_picture_header(MpegEncContext *s)
     // hack for AMV mjpeg format
     if(s->avctx->codec_id == AV_CODEC_ID_AMV) goto end;
 
-    jpeg_put_comments(s);
+    jpeg_put_comments(s->avctx, &s->pb);
 
     jpeg_table_header(s);