diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index c4199cf110..11048670af 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -53,6 +53,7 @@ typedef struct Mpeg1Context {
     AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator
     int sync;                        ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?
     int tmpgexs;
+    int first_slice;
     int extradata_decoded;
 } Mpeg1Context;
 
@@ -1955,7 +1956,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
 #endif /* FF_API_XVMC */
 
     /* end of slice reached */
-    if (/*s->mb_y << field_pic == s->mb_height &&*/ !s->first_field && !s->first_slice) {
+    if (/*s->mb_y << field_pic == s->mb_height &&*/ !s->first_field && !s1->first_slice) {
         /* end of image */
 
         ff_er_frame_end(&s->er);
@@ -2352,7 +2353,7 @@ static int decode_chunks(AVCodecContext *avctx,
                 /* we have a complete image: we try to decompress it */
                 if (mpeg1_decode_picture(avctx, buf_ptr, input_size) < 0)
                     s2->pict_type = 0;
-                s2->first_slice = 1;
+                s->first_slice = 1;
                 last_code = PICTURE_START_CODE;
             } else {
                 av_log(avctx, AV_LOG_ERROR, "ignoring pic after %X\n", last_code);
@@ -2496,9 +2497,9 @@ static int decode_chunks(AVCodecContext *avctx,
                     break;
                 }
 
-                if (s2->first_slice) {
+                if (s->first_slice) {
                     skip_frame = 0;
-                    s2->first_slice = 0;
+                    s->first_slice = 0;
                     if (mpeg_field_start(s2, buf, buf_size) < 0)
                         return -1;
                 }
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index c0259aa8b2..b1224bcf5d 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -685,7 +685,6 @@ typedef struct MpegEncContext {
     int progressive_frame;
     int full_pel[2];
     int interlaced_dct;
-    int first_slice;
     int first_field;         ///< is 1 for the first field of a field picture 0 otherwise
     int drop_frame_timecode; ///< timecode is in drop frame format.
     int scan_offset;         ///< reserve space for SVCD scan offset user data.