diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 19d44e4bd7..4c8015f44e 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1168,6 +1168,8 @@ int ff_mjpeg_decode_sos(MJpegDecodeContext *s, const uint8_t *mb_bitmask,
 
         if(nb_components == 3 && s->nb_components == 3 && s->avctx->pix_fmt == PIX_FMT_GBR24P)
             index = (i+2)%3;
+        if(nb_components == 1 && s->nb_components == 3 && s->avctx->pix_fmt == PIX_FMT_GBR24P)
+            index = (index+2)%3;
 
         s->comp_index[i] = index;