diff --git a/ChangeLog b/ChangeLog
index 8ef45992..b3fdfcd4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-02-28  Federico Di Gregorio  <fog@initd.org>
+
+	* psycopg/adapt_decimal.c: Python 2.4 decimal type does not support
+	.isfinite() and two different calls to ._isinfinity() and ._isnan() are
+	required. This fixes both a test failure and a segfault.
+
+
 2010-02-15  Federico Di Gregorio  <fog@initd.org>
 
 	* Added new Decimal adapter that correctly converts NaN and infinity
diff --git a/psycopg/adapter_pdecimal.c b/psycopg/adapter_pdecimal.c
index 11d25950..6bcccb58 100644
--- a/psycopg/adapter_pdecimal.c
+++ b/psycopg/adapter_pdecimal.c
@@ -42,14 +42,29 @@
 static PyObject *
 pdecimal_str(pdecimalObject *self)
 {
-    PyObject *res = NULL;
-    PyObject *check = PyObject_CallMethod(self->wrapped, "is_finite", NULL);
-
+    PyObject *check, *res = NULL;
+#if PY_VERSION_HEX < 0x02050000
+    check = PyObject_CallMethod(self->wrapped, "_isnan", NULL);
+    if (PyInt_AsLong(check) == 1) {
+        res = PyString_FromString("'NaN'::numeric");
+        goto end;
+    }
+    Py_DECREF(check);
+    check = PyObject_CallMethod(self->wrapped, "_isinfinity", NULL);
+    if (abs(PyInt_AsLong(check)) == 1) {
+        res = PyString_FromString("'NaN'::numeric");
+        goto end;
+    }
+    res = PyObject_Str(self->wrapped);
+#else
+    check = PyObject_CallMethod(self->wrapped, "is_finite", NULL);
     if (check == Py_True)
         res = PyObject_Str(self->wrapped);
     else
         res = PyString_FromString("'NaN'::numeric");
+#endif
 
+   end:
     Py_DECREF(check);
     return res;
 }