diff --git a/libavcodec/mpeg4video.h b/libavcodec/mpeg4video.h
index 24e25880f5..1f064c84ed 100644
--- a/libavcodec/mpeg4video.h
+++ b/libavcodec/mpeg4video.h
@@ -59,6 +59,10 @@
 #define VISUAL_OBJ_STARTCODE 0x1B5
 #define VOP_STARTCODE        0x1B6
 
+typedef struct Mpeg4DecContext {
+    MpegEncContext m;
+} Mpeg4DecContext;
+
 /* dc encoding for mpeg4 */
 extern const uint8_t ff_mpeg4_DCtab_lum[13][2];
 extern const uint8_t ff_mpeg4_DCtab_chrom[13][2];
diff --git a/libavcodec/mpeg4video_parser.c b/libavcodec/mpeg4video_parser.c
index 6a8cb6f7cc..26a4dd3789 100644
--- a/libavcodec/mpeg4video_parser.c
+++ b/libavcodec/mpeg4video_parser.c
@@ -30,7 +30,7 @@
 
 struct Mp4vParseContext {
     ParseContext pc;
-    struct MpegEncContext enc;
+    Mpeg4DecContext dec_ctx;
     int first_picture;
 };
 
@@ -78,7 +78,8 @@ static int av_mpeg4_decode_header(AVCodecParserContext *s1,
                                   const uint8_t *buf, int buf_size)
 {
     struct Mp4vParseContext *pc = s1->priv_data;
-    MpegEncContext *s = &pc->enc;
+    Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
+    MpegEncContext *s = &dec_ctx->m;
     GetBitContext gb1, *gb = &gb1;
     int ret;
 
@@ -117,9 +118,9 @@ static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
     ff_mpeg4videodec_static_init();
 
     pc->first_picture           = 1;
-    pc->enc.quant_precision     = 5;
-    pc->enc.slice_context_count = 1;
-    pc->enc.showed_packed_warning = 1;
+    pc->dec_ctx.m.quant_precision     = 5;
+    pc->dec_ctx.m.slice_context_count = 1;
+    pc->dec_ctx.m.showed_packed_warning = 1;
     return 0;
 }
 
diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index b6a8faf313..50de9eca81 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -2501,9 +2501,24 @@ av_cold void ff_mpeg4videodec_static_init(void) {
     }
 }
 
+static int mpeg4_update_thread_context(AVCodecContext *dst,
+                                       const AVCodecContext *src)
+{
+    Mpeg4DecContext *s = dst->priv_data;
+    const Mpeg4DecContext *s1 = src->priv_data;
+
+    int ret = ff_mpeg_update_thread_context(dst, src);
+
+    if (ret < 0)
+        return ret;
+
+    return 0;
+}
+
 static av_cold int decode_init(AVCodecContext *avctx)
 {
-    MpegEncContext *s = avctx->priv_data;
+    Mpeg4DecContext *ctx = avctx->priv_data;
+    MpegEncContext *s = &ctx->m;
     int ret;
 
     s->divx_version =
@@ -2572,7 +2587,7 @@ AVCodec ff_mpeg4_decoder = {
     .long_name             = NULL_IF_CONFIG_SMALL("MPEG-4 part 2"),
     .type                  = AVMEDIA_TYPE_VIDEO,
     .id                    = AV_CODEC_ID_MPEG4,
-    .priv_data_size        = sizeof(MpegEncContext),
+    .priv_data_size        = sizeof(Mpeg4DecContext),
     .init                  = decode_init,
     .close                 = ff_h263_decode_end,
     .decode                = ff_h263_decode_frame,
@@ -2583,7 +2598,7 @@ AVCodec ff_mpeg4_decoder = {
     .max_lowres            = 3,
     .pix_fmts              = ff_h263_hwaccel_pixfmt_list_420,
     .profiles              = NULL_IF_CONFIG_SMALL(mpeg4_video_profiles),
-    .update_thread_context = ONLY_IF_THREADS_ENABLED(ff_mpeg_update_thread_context),
+    .update_thread_context = ONLY_IF_THREADS_ENABLED(mpeg4_update_thread_context),
     .priv_class = &mpeg4_class,
 };