Index: Lib/ctypes/test/test_bitfields.py
===================================================================
--- Lib/ctypes/test/test_bitfields.py	(revision 66506)
+++ Lib/ctypes/test/test_bitfields.py	(working copy)
@@ -215,6 +215,16 @@
                         ("b", c_ubyte, 4)]
         self.failUnlessEqual(sizeof(X), sizeof(c_byte))
 
+    def test_mixed_4(self):
+        class X(Structure):
+            _fields_ = [("a", c_short, 4),
+                        ("b", c_short, 4),
+                        ("c", c_int, 24),
+                        ("d", c_short, 4),
+                        ("e", c_short, 4),
+                        ("f", c_int, 24)]
+        self.failUnlessEqual(sizeof(X), sizeof(c_int) * 2)
+
     def test_anon_bitfields(self):
         # anonymous bit-fields gave a strange error message
         class X(Structure):
Index: Misc/NEWS
===================================================================
--- Misc/NEWS	(revision 66506)
+++ Misc/NEWS	(working copy)
@@ -15,6 +15,8 @@
 Library
 -------
 
+- Issue #3547: Fixed ctypes structures bitfields of varying integer
+  sizes.
 
 What's New in Python 2.6 release candidate 2?
 =============================================
Index: Modules/_ctypes/cfield.c
===================================================================
--- Modules/_ctypes/cfield.c	(revision 66506)
+++ Modules/_ctypes/cfield.c	(working copy)
@@ -163,7 +163,7 @@
 		break;
 
 	case EXPAND_BITFIELD:
-		/* XXX needs more */
+		*poffset += dict->size - *pfield_size/8;
 		*psize += dict->size - *pfield_size/8;
 
 		*pfield_size = dict->size * 8;