Index: Modules/_bytesio.c
===================================================================
--- Modules/_bytesio.c	(révision 66621)
+++ Modules/_bytesio.c	(copie de travail)
@@ -221,6 +221,8 @@
 
     if (PyInt_Check(arg)) {
         size = PyInt_AsSsize_t(arg);
+        if (size == -1 && PyErr_Occured())
+            return NULL;
     }
     else if (arg == Py_None) {
         /* Read until EOF is reached, by default. */
@@ -288,6 +290,8 @@
 
     if (PyInt_Check(arg)) {
         size = PyInt_AsSsize_t(arg);
+        if (size == -1 && PyErr_Occured())
+            return NULL;
     }
     else if (arg == Py_None) {
         /* No size limit, by default. */
@@ -332,6 +336,8 @@
 
     if (PyInt_Check(arg)) {
         maxsize = PyInt_AsSsize_t(arg);
+        if (maxsize == -1 && PyErr_Occured())
+            return NULL;
     }
     else if (arg == Py_None) {
         /* No size limit, by default. */
@@ -415,6 +421,8 @@
 
     if (PyInt_Check(arg)) {
         size = PyInt_AsSsize_t(arg);
+        if (size == -1 && PyErr_Occured())
+            return NULL;
     }
     else if (arg == Py_None) {
         /* Truncate to current position if no argument is passed. */