diff -r e38d975da53e Modules/_tracemalloc.c
--- a/Modules/_tracemalloc.c	Wed Nov 20 22:01:42 2013 +0100
+++ b/Modules/_tracemalloc.c	Wed Nov 20 22:49:53 2013 +0100
@@ -71,7 +71,12 @@ static PyThread_type_lock tables_lock;
 #  define TABLES_UNLOCK()
 #endif
 
-typedef struct {
+#pragma pack(4)
+typedef struct
+#ifdef __GNUC__
+__attribute__((packed))
+#endif
+{
     PyObject *filename;
     int lineno;
 } frame_t;
@@ -657,6 +662,9 @@ tracemalloc_init(void)
     if (tracemalloc_config.initialized == TRACEMALLOC_INITIALIZED)
         return 0;
 
+    /* ensure that the frame_t structure is packed */
+    assert(sizeof(frame_t) == (sizeof(PyObject*) + sizeof(int)));
+
     PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
 
 #ifdef REENTRANT_THREADLOCAL