diff -r d229032dc213 Modules/_randommodule.c
--- a/Modules/_randommodule.c	Tue Apr 17 22:48:06 2012 -0400
+++ b/Modules/_randommodule.c	Thu Apr 19 08:15:29 2012 +0100
@@ -427,8 +427,19 @@
         mt[j] = tmp;
     }
 
-    for (i = 0; i < N; i++)
+    for (i = 0; i < N; i++) {
         mt[i] += i+1;
+        mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+    }
+
+    /* Make sure the state is nonzero: in the unlikely event that mt[1] through
+       mt[N-1] are all zero, we set the MSB of mt[0]. */
+    tmp = 0;
+    for (i = 1; i < N; i++) {
+        tmp |= mt[i];
+    }
+    if (tmp == 0)
+        mt[0] = 0x80000000UL;
 
     self->index = N;
     Py_INCREF(Py_None);