diff -Naur mpfr-2.1.1-p9/atan.c mpfr-2.1.1-p10/atan.c
--- mpfr-2.1.1-p9/atan.c	2004-06-16 12:08:30.000000000 +0000
+++ mpfr-2.1.1-p10/atan.c	2005-07-05 13:00:43.000000000 +0000
@@ -1,6 +1,6 @@
 /* mpfr_atan -- arc-tangent of a floating-point number
 
-Copyright 2001, 2002, 2003, 2004 Free Software Foundation.
+Copyright 2001, 2002, 2003, 2004, 2005 Free Software Foundation.
 
 This file is part of the MPFR Library, and was contributed by Mathieu Dutour.
 
@@ -107,7 +107,8 @@
       else /* x is necessarily 0 */
 	{
           MPFR_ASSERTD(MPFR_IS_ZERO(x));
-	  mpfr_set_ui (arctangent, 0, GMP_RNDN);
+          MPFR_SET_ZERO (arctangent);
+          MPFR_SET_SAME_SIGN (arctangent, x);
 	  return 0; /* exact result */
 	}
     }
diff -Naur mpfr-2.1.1-p9/tests/tatan.c mpfr-2.1.1-p10/tests/tatan.c
--- mpfr-2.1.1-p9/tests/tatan.c	2005-02-04 12:28:53.000000000 +0000
+++ mpfr-2.1.1-p10/tests/tatan.c	2005-07-05 12:57:44.000000000 +0000
@@ -93,19 +93,33 @@
 
   /* atan(+/-0) = +/-0 */
   mpfr_set_ui (x, 0, GMP_RNDN);
+  MPFR_SET_NEG (y);
   mpfr_atan (y, x, GMP_RNDN);
-  if (mpfr_cmp_ui (y, 0) || mpfr_sgn (y) < 0)
+  if (mpfr_cmp_ui (y, 0) || MPFR_IS_NEG (y))
     {
       printf ("Error: mpfr_atan (+0) <> +0\n");
       exit (1);
     }
+  mpfr_atan (x, x, GMP_RNDN);
+  if (mpfr_cmp_ui (x, 0) || MPFR_IS_NEG (x))
+    {
+      printf ("Error: mpfr_atan (+0) <> +0 (in place)\n");
+      exit (1);
+    }
   mpfr_neg (x, x, GMP_RNDN);
+  MPFR_SET_POS (y);
   mpfr_atan (y, x, GMP_RNDN);
-  if (mpfr_cmp_ui (y, 0) || mpfr_sgn (y) > 0)
+  if (mpfr_cmp_ui (y, 0) || MPFR_IS_POS (y))
     {
       printf ("Error: mpfr_atan (-0) <> -0\n");
       exit (1);
     }
+  mpfr_atan (x, x, GMP_RNDN);
+  if (mpfr_cmp_ui (x, 0) || MPFR_IS_POS (x))
+    {
+      printf ("Error: mpfr_atan (-0) <> -0 (in place)\n");
+      exit (1);
+    }
 
   mpfr_set_prec (x, 32);
   mpfr_set_prec (y, 32);