diff --git a/ChangeLog b/ChangeLog
index 1cc19899de..acba651c9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Oct  2 02:04:12 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* string.c (rb_str_hash_m): st_index_t is not guaranteed as the same
+	  size with int, and of course also not guaranteed the value can be
+	  Fixnum.
+
 Sun Oct  2 02:03:06 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* numeric.c (rb_fix2str): detect unnormalized Fixnum value.
diff --git a/string.c b/string.c
index 8a57bc9048..1c27c89e8b 100644
--- a/string.c
+++ b/string.c
@@ -2963,7 +2963,13 @@ static VALUE
 rb_str_hash_m(VALUE str)
 {
     st_index_t hval = rb_str_hash(str);
-    return INT2FIX(hval);
+#if SIZEOF_LONG == SIZEOF_VOIDP
+    return ULONG2NUM(hval);
+#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
+    return ULL2NUM(hval);
+#else
+# error unsupported platform
+#endif
 }
 
 #define lesser(a,b) (((a)>(b))?(b):(a))