diff -Naur mpfr-2.1.2/exp.c mpfr-2.1.2-p1/exp.c
--- mpfr-2.1.2/exp.c	2005-01-29 11:42:08.000000000 +0000
+++ mpfr-2.1.2-p1/exp.c	2005-09-13 14:53:34.000000000 +0000
@@ -83,7 +83,8 @@
       int signx = MPFR_SIGN(x);
 
       MPFR_SET_POS(y);
-      if (MPFR_IS_NEG_SIGN(signx) && (rnd_mode == GMP_RNDD))
+      if (MPFR_IS_NEG_SIGN(signx) && (rnd_mode == GMP_RNDD ||
+                                      rnd_mode == GMP_RNDZ))
         {
           mpfr_setmax (y, 0);  /* y = 1 - epsilon */
           return -1;
diff -Naur mpfr-2.1.2/tests/texp.c mpfr-2.1.2-p1/tests/texp.c
--- mpfr-2.1.2/tests/texp.c	2005-03-09 07:58:55.000000000 +0000
+++ mpfr-2.1.2-p1/tests/texp.c	2005-09-13 14:53:35.000000000 +0000
@@ -250,12 +250,16 @@
   if (mpfr_cmp_ui_2exp (y, 3, -2))
     {
       printf ("Error for exp(-1/16), prec=2, RNDD\n");
+      printf ("expected 0.11, got ");
+      mpfr_dump (y);
       exit (1);
     }
   mpfr_exp (y, x, GMP_RNDZ);
-  if (mpfr_cmp_ui (y, 1))
+  if (mpfr_cmp_ui_2exp (y, 3, -2))
     {
       printf ("Error for exp(-1/16), prec=2, RNDZ\n");
+      printf ("expected 0.11, got ");
+      mpfr_dump (y);
       exit (1);
     }
   mpfr_set_str_binary (x, "0.1E-3");
@@ -361,6 +365,16 @@
       mpfr_out_str (stdout, 16, 0, x, GMP_RNDN); putchar ('\n');
     }
 
+  /* bug found by Guillaume Melquiond, 13 Sep 2005 */
+  mpfr_set_prec (x, 53);
+  mpfr_set_str_binary (x, "-1E-400");
+  mpfr_exp (x, x, GMP_RNDZ);
+  if (mpfr_cmp_ui (x, 1) == 0)
+    {
+      printf ("Error for exp(-2^(-400))\n");
+      exit (1);
+    }
+
   mpfr_clear (x);
   mpfr_clear (y);
 }