--- numbers.c.~1.206.~	1970-01-01 10:00:01.000000000 +1000
+++ numbers.c	2003-11-13 08:31:33.000000000 +1000
@@ -468,7 +468,14 @@
 	return x;
     }
   else if (SCM_REALP (x))
-    return scm_make_real (fabs (SCM_REAL_VALUE (x)));
+    {
+      /* note that if x is a NaN then xx<0 is false so we return x unchanged */
+      double xx = SCM_REAL_VALUE (x);
+      if (xx < 0.0)
+        return scm_make_real (-xx);
+      else
+        return x;
+    }
   else
     SCM_WTA_DISPATCH_1 (g_scm_abs, x, 1, s_scm_abs);
 }