diff --git a/libavcodec/pnm_parser.c b/libavcodec/pnm_parser.c
index 29183f8f31..10a215f3c6 100644
--- a/libavcodec/pnm_parser.c
+++ b/libavcodec/pnm_parser.c
@@ -108,7 +108,7 @@ retry:
     } else {
         int ret = av_image_get_buffer_size(avctx->pix_fmt, avctx->width, avctx->height, 1);
         next = pnmctx.bytestream - pnmctx.bytestream_start + skip;
-        if (ret >= 0)
+        if (ret >= 0 && next + (uint64_t)ret <= INT_MAX)
             next += ret;
     }
     if (next != END_NOT_FOUND && pnmctx.bytestream_start != buf + skip)