diff --git a/ChangeLog b/ChangeLog
index d7b1164923..4f2c6da71d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Apr 13 00:12:04 2010  Tanaka Akira  <akr@fsij.org>
+
+	* random.c (rand_init): use the absolute value of seed to
+	  make srand(-2**40) portable with 32bit and 64bit.
+	  [ruby-core:29292](2)
+
 Mon Apr 12 22:48:47 2010  Tanaka Akira  <akr@fsij.org>
 
 	* enumerator.c (inspect_enumerator): don't raise for uninitialized
diff --git a/random.c b/random.c
index de047995d5..149069c76e 100644
--- a/random.c
+++ b/random.c
@@ -376,6 +376,8 @@ rand_init(struct MT *mt, VALUE vseed)
       case T_FIXNUM:
 	len = 1;
 	fixnum_seed = FIX2LONG(seed);
+        if (fixnum_seed < 0)
+            fixnum_seed = -fixnum_seed;
 	buf[0] = (unsigned int)(fixnum_seed & 0xffffffff);
 #if SIZEOF_LONG > SIZEOF_INT32
 	if ((long)(int)fixnum_seed != fixnum_seed) {