diff --git a/ffmpeg_filter.c b/ffmpeg_filter.c
index 8a96c4be86..6a59f0547b 100644
--- a/ffmpeg_filter.c
+++ b/ffmpeg_filter.c
@@ -682,8 +682,8 @@ static int sub2video_prepare(InputStream *ist)
         }
         av_log(avf, AV_LOG_INFO, "sub2video: using %dx%d canvas\n", w, h);
     }
-    ist->sub2video.w = ist->dec_ctx->width  = ist->resample_width  = w;
-    ist->sub2video.h = ist->dec_ctx->height = ist->resample_height = h;
+    ist->sub2video.w = ist->resample_width  = w;
+    ist->sub2video.h = ist->resample_height = h;
 
     /* rectangles are AV_PIX_FMT_PAL8, but we have no guarantee that the
        palettes for all rectangles are identical or compatible */