diff -Naur mpfr-2.1.1/exp_2.c mpfr-2.1.1-p1/exp_2.c
--- mpfr-2.1.1/exp_2.c	2004-08-24 14:00:42.000000000 +0000
+++ mpfr-2.1.1-p1/exp_2.c	2005-03-09 07:52:34.226856000 +0000
@@ -1,7 +1,7 @@
 /* mpfr_exp_2 -- exponential of a floating-point number
                 using Brent's algorithms in O(n^(1/2)*M(n)) and O(n^(1/3)*M(n))
 
-Copyright 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
 
 This file is part of the MPFR Library.
 
@@ -147,7 +147,7 @@
       mpfr_sub (r, x, r, GMP_RNDU);
       /* possible cancellation here: the error on r is at most
 	 3*2^(EXP(old_r)-EXP(new_r)) */
-      if (MPFR_IS_NEG (r))
+      while (MPFR_IS_NEG (r))
 	{ /* initial approximation n was too large */
 	  n--;
 	  mpfr_add (r, r, s, GMP_RNDU);
diff -Naur mpfr-2.1.1/tests/texp.c mpfr-2.1.1-p1/tests/texp.c
--- mpfr-2.1.1/tests/texp.c	2005-01-29 11:36:41.000000000 +0000
+++ mpfr-2.1.1-p1/tests/texp.c	2005-03-05 01:25:57.000000000 +0000
@@ -346,6 +346,21 @@
       exit (1);
     }
 
+  /* Bug due to wrong approximation of (x)/log2 */
+  mpfr_set_prec (x, 163);
+
+  mpfr_set_str (x, "-4.28ac8fceeadcda06bb56359017b1c81b85b392e7", 16,
+		GMP_RNDN);
+  mpfr_exp (x, x, GMP_RNDN);
+  if (mpfr_cmp_str (x, "3.fffffffffffffffffffffffffffffffffffffffe8@-2",
+		    16, GMP_RNDN))
+    {
+      printf ("Error for x= -4.28ac8fceeadcda06bb56359017b1c81b85b392e7");
+      printf ("expected  3.fffffffffffffffffffffffffffffffffffffffe8@-2");
+      printf ("Got       ");
+      mpfr_out_str (stdout, 16, 0, x, GMP_RNDN); putchar ('\n');
+    }
+
   mpfr_clear (x);
   mpfr_clear (y);
 }