diff --git a/apps/errstr.c b/apps/errstr.c
index 99bb9e9068f27186a0e77361986c82c6def951c9..141338adac4bd7c0966ec6247aa7f6ead1c9db1e 100644
--- a/apps/errstr.c
+++ b/apps/errstr.c
@@ -111,7 +111,7 @@ int errstr_main(int argc, char **argv)
 
     ret = 0;
     for (argv = opt_rest(); *argv; argv++) {
-        if (!opt_ulong(*argv, &l))
+        if (sscanf(*argv, "%lx", &l) == 0)
             ret++;
         else {
             /* We're not really an SSL application so this won't auto-init, but