diff --git a/ChangeLog b/ChangeLog
index 4d42709f0c..449e122b59 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Nov 28 09:18:39 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* string.c (rb_fstring): fstrings should be ELTS_SHARED.
+	  If we resurrect dying objects (non-marked, but not swept yet),
+	  pointing shared string can be collected.
+	  To avoid such issue, fstrings (recorded to fstring_table)
+	  should not be ELTS_SHARED (should not have a shared string).
+
 Thu Nov 28 01:35:08 2013  Masaki Matsushita  <glass.saga@gmail.com>
 
 	* st.c (st_keys): fix to use st_index_t for size of hash.
diff --git a/string.c b/string.c
index c6c1497ea4..231bb2f4fd 100644
--- a/string.c
+++ b/string.c
@@ -148,7 +148,14 @@ rb_fstring(VALUE str)
 	rb_gc_resurrect(str);
     }
     else {
-	str = rb_str_new_frozen(str);
+	if (STR_SHARED_P(str)) {
+	    /* str should not be shared */
+	    str = rb_enc_str_new(RSTRING_PTR(str), RSTRING_LEN(str), STR_ENC_GET(str));
+	    OBJ_FREEZE(str);
+	}
+	else {
+	    str = rb_str_new_frozen(str);
+	}
 	RBASIC(str)->flags |= RSTRING_FSTR;
 	st_insert(frozen_strings, str, str);
     }