diff --git a/string.c b/string.c
index c268cd6248..d41a5314e1 100644
--- a/string.c
+++ b/string.c
@@ -2337,7 +2337,7 @@ rb_str_hash_cmp(VALUE str1, VALUE str2)
  * call-seq:
  *    str.hash   -> fixnum
  *
- * Return a hash based on the string's length and content.
+ * Return a hash based on the string's length, content and encoding.
  */
 
 static VALUE