diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1259,6 +1259,8 @@
 
 Extension Modules
 -----------------
+- Bug #2122: flush method of mmap objects now returns None and raises 
+  an Exception on errors.
 
 - Patch #1506171: added operator.methodcaller().
 
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -534,7 +534,12 @@
 		return NULL;
 	}
 #ifdef MS_WINDOWS
-	return PyInt_FromLong((long) FlushViewOfFile(self->data+offset, size));
+        if (!FlushViewOfFile(self->data+offset, size)) {
+                PyErr_SetFromWindowsErr(GetLastError());
+                return NULL;
+        }
+        Py_INCREF(Py_None);
+        return Py_None;
 #elif defined(UNIX)
 	/* XXX semantics of return value? */
 	/* XXX flags for msync? */
@@ -542,7 +547,8 @@
 		PyErr_SetFromErrno(mmap_module_error);
 		return NULL;
 	}
-	return PyInt_FromLong(0);
+        Py_INCREF(Py_None);
+        return Py_None;
 #else
 	PyErr_SetString(PyExc_ValueError, "flush not supported on this system");
 	return NULL;