diff --git a/lib/pari.c b/lib/pari.c
index f3abf2cfa406bb2a6217e9709d7f56363e146584..984fe2d5f1c2753e0f93f52f4b9f6b6e757813cf 100644
--- a/lib/pari.c
+++ b/lib/pari.c
@@ -197,7 +197,8 @@ void cm_pari_init ()
    pari_init_opts (1ul<<23, 0, INIT_JMPm | INIT_DFTm | INIT_noIMTm);
       /* Do not capture SIGSEGV. */
    paristack_setsize (1ul<<23, 1ul<<31);
-   sd_threadsizemax ("1G", d_SILENT);
+   if (sizeof (long int) * CHAR_BIT >= 64)
+     sd_threadsizemax ("1G", d_SILENT);
    pari_add_module (functions_gp);
    pari_mt_init ();
 }