diff --git a/Changelog b/Changelog
index 6442a89148..dfee2e65e8 100644
--- a/Changelog
+++ b/Changelog
@@ -13,6 +13,7 @@ version <next>:
 - indeo3: use unaligned reads on reference blocks, Bug #503
 - oma: properly forward errors in oma_read_packet
 - af_asyncts: fix offset calculation
+- proresdec: support mixed interlaced/non-interlaced content
 
 Most of the following fixes resulted from test samples that the Google
 Security Team has kindly made available to us:
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index b1aff360d2..a59ba3b046 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1676,6 +1676,13 @@ int ff_mjpeg_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                 mjpeg_decode_com(s);
 
             ret = -1;
+
+            if (!CONFIG_JPEGLS_DECODER &&
+                (start_code == SOF48 || start_code == LSE)) {
+                av_log(avctx, AV_LOG_ERROR, "JPEG-LS support not enabled.\n");
+                return AVERROR(ENOSYS);
+            }
+
             switch (start_code) {
             case SOI:
                 s->restart_interval = 0;
diff --git a/libavcodec/proresdec_lgpl.c b/libavcodec/proresdec_lgpl.c
index 4fa2817e86..a25ecca3c9 100644
--- a/libavcodec/proresdec_lgpl.c
+++ b/libavcodec/proresdec_lgpl.c
@@ -164,6 +164,8 @@ static int decode_frame_header(ProresContext *ctx, const uint8_t *buf,
     if (ctx->frame_type) {      /* if interlaced */
         ctx->picture.interlaced_frame = 1;
         ctx->picture.top_field_first  = ctx->frame_type & 1;
+    } else {
+        ctx->picture.interlaced_frame = 0;
     }
 
     avctx->color_primaries = buf[14];