diff --git a/ChangeLog b/ChangeLog
index b80165670d..5cdfe6ceda 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul  1 11:41:12 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* string.c (tr_trans): free heap ptr when the str is not embeded.
+	  patched by Eric Wong. [Bug #4956] [ruby-core:37708]
+
 Fri Jul  1 11:07:43 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* thread.c (do_select): fix memory leak.
diff --git a/string.c b/string.c
index 9a85f81493..711918b4e6 100644
--- a/string.c
+++ b/string.c
@@ -5117,6 +5117,9 @@ tr_trans(VALUE str, VALUE src, VALUE repl, int sflag)
 	    CHECK_IF_ASCII(c);
 	    t += tlen;
 	}
+	if (!STR_EMBED_P(str)) {
+	    xfree(RSTRING(str)->as.heap.ptr);
+	}
 	*t = '\0';
 	RSTRING(str)->as.heap.ptr = buf;
 	RSTRING(str)->as.heap.len = t - buf;