diff --git a/src/emacs.c b/src/emacs.c
index 1fecf1fa4b4..92f6bfe636f 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1060,6 +1060,7 @@ load_seccomp (const char *file)
       emacs_perror ("read");
       goto out;
     }
+  eassert (read <= SIZE_MAX);
   if (read != size)
     {
       fprintf (stderr,