diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index ade5efe..ece709c 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -137,6 +137,20 @@
     return flag;
 }
 
+static int
+isatty_no_error(PyObject *sys_stream)
+{
+    PyObject *sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
+    if (sys_isatty) {
+        int isatty = PyObject_IsTrue(sys_isatty);
+        Py_DECREF(sys_isatty);
+        if (isatty >= 0)
+            return isatty;
+    }
+    PyErr_Clear();
+    return 0;
+}
+
 void
 Py_InitializeEx(int install_sigs)
 {
@@ -150,7 +164,7 @@
     char *errors = NULL;
     int free_codeset = 0;
     int overridden = 0;
-    PyObject *sys_stream, *sys_isatty;
+    PyObject *sys_stream;
 #if defined(Py_USING_UNICODE) && defined(HAVE_LANGINFO_H) && defined(CODESET)
     char *saved_locale, *loc_codeset;
 #endif
@@ -336,40 +350,25 @@
 
     if (codeset) {
         sys_stream = PySys_GetObject("stdin");
-        sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
-        if (!sys_isatty)
-            PyErr_Clear();
-        if ((overridden ||
-             (sys_isatty && PyObject_IsTrue(sys_isatty))) &&
-           PyFile_Check(sys_stream)) {
+        if ((overridden || isatty_no_error(sys_stream)) &&
+            PyFile_Check(sys_stream)) {
             if (!PyFile_SetEncodingAndErrors(sys_stream, icodeset, errors))
                 Py_FatalError("Cannot set codeset of stdin");
         }
-        Py_XDECREF(sys_isatty);
 
         sys_stream = PySys_GetObject("stdout");
-        sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
-        if (!sys_isatty)
-            PyErr_Clear();
-        if ((overridden ||
-             (sys_isatty && PyObject_IsTrue(sys_isatty))) &&
-           PyFile_Check(sys_stream)) {
+        if ((overridden || isatty_no_error(sys_stream)) &&
+            PyFile_Check(sys_stream)) {
             if (!PyFile_SetEncodingAndErrors(sys_stream, codeset, errors))
                 Py_FatalError("Cannot set codeset of stdout");
         }
-        Py_XDECREF(sys_isatty);
 
         sys_stream = PySys_GetObject("stderr");
-        sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
-        if (!sys_isatty)
-            PyErr_Clear();
-        if((overridden ||
-            (sys_isatty && PyObject_IsTrue(sys_isatty))) &&
-           PyFile_Check(sys_stream)) {
+        if ((overridden || isatty_no_error(sys_stream)) &&
+            PyFile_Check(sys_stream)) {
             if (!PyFile_SetEncodingAndErrors(sys_stream, codeset, errors))
                 Py_FatalError("Cannot set codeset of stderr");
         }
-        Py_XDECREF(sys_isatty);
 
         if (free_codeset)
             free(codeset);