diff --git a/ChangeLog b/ChangeLog
index 92b2edc31a..28a684539a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jun 21 16:13:45 2016  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* string.c (rb_str_casemap): fix memory leak.
+
 Tue Jun 21 16:12:21 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* string.c (rb_str_casemap): int is too small for string size.
diff --git a/string.c b/string.c
index 93d247f57e..a62ae2dd8d 100644
--- a/string.c
+++ b/string.c
@@ -5809,8 +5809,10 @@ rb_str_casemap(VALUE source, OnigCaseFoldType *flags, rb_encoding *enc)
     }
 /* fprintf(stderr, "Buffer count is %d\n", buffer_count); *//* for tuning */
 
-    if (buffer_count==1)
+    if (buffer_count==1) {
 	target = rb_str_new_with_class(source, (const char*)current_buffer->space, target_length);
+	    xfree(current_buffer);
+    }
     else {
 	char *target_current = RSTRING_PTR(target = rb_str_new_with_class(source, 0, target_length));
 	mapping_buffer *previous_buffer;