diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index 427554c..a8b08cd 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -1415,7 +1415,6 @@ static int h264_slice_header_parse(H264Context *h, H264SliceContext *sl)
     }

     if (!h->context_initialized || must_reinit || needs_reinit) {
-        h->context_initialized = 0;
         if (sl != h->slice_ctx) {
             av_log(h->avctx, AV_LOG_ERROR,
                    "changing width %d -> %d / height %d -> %d on "
@@ -1428,8 +1427,10 @@ static int h264_slice_header_parse(H264Context *h, H264SliceContext *sl)

         av_assert1(first_slice);

-        ff_h264_flush_change(h);
+        if(h->context_initialized)
+            ff_h264_flush_change(h);

+        h->context_initialized = 0;
         if ((ret = get_pixel_format(h, 1)) < 0)
             return ret;
         h->avctx->pix_fmt = ret;