Index: Lib/test/test_mmap.py
===================================================================
--- Lib/test/test_mmap.py	(révision 60801)
+++ Lib/test/test_mmap.py	(copie de travail)
@@ -426,7 +426,14 @@
                 return mmap.mmap.__new__(klass, -1, *args, **kwargs)
         anon_mmap(PAGESIZE)
 
+    def test_prot_readonly(self):
+        mapsize = 10
+        open(TESTFN, "wb").write("a"*mapsize)
+        f = open(TESTFN, "rb")
+        m = mmap.mmap(f.fileno(), mapsize, prot=mmap.PROT_READ)
+        self.assertRaises(TypeError, m.write, "foo")
 
+
 def test_main():
     run_unittest(MmapTests)
 
Index: Modules/mmapmodule.c
===================================================================
--- Modules/mmapmodule.c	(révision 60801)
+++ Modules/mmapmodule.c	(copie de travail)
@@ -1122,6 +1122,10 @@
 				    "mmap invalid access parameter.");
 	}
 
+    if (prot == PROT_READ) {
+        access = ACCESS_READ;
+    }
+
 #ifdef HAVE_FSTAT
 #  ifdef __VMS
 	/* on OpenVMS we must ensure that all bytes are written to the file */