diff --git a/ChangeLog b/ChangeLog
index 30e578818a..cb85a8a900 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Oct 24 12:47:47 2015  Martin Duerst  <duerst@it.aoyama.ac.jp>
+
+	* vm_insnhelper.c: improved error message for "wrong number
+	  of arguments", distinguishing given and expected argument
+	  numbers clearly. [Feature #9025]
+
 Sat Oct 24 11:57:59 2015  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* vm_insnhelper.c: remove the typedef redeclaration of
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 7f4a371423..07b7b02385 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -216,13 +216,13 @@ rb_arity_error_new(int argc, int min, int max)
 {
     VALUE err_mess = 0;
     if (min == max) {
-	err_mess = rb_sprintf("wrong number of arguments (%d for %d)", argc, min);
+	err_mess = rb_sprintf("wrong number of arguments (given %d, expected %d)", argc, min);
     }
     else if (max == UNLIMITED_ARGUMENTS) {
-	err_mess = rb_sprintf("wrong number of arguments (%d for %d+)", argc, min);
+	err_mess = rb_sprintf("wrong number of arguments (given %d, expected %d+)", argc, min);
     }
     else {
-	err_mess = rb_sprintf("wrong number of arguments (%d for %d..%d)", argc, min, max);
+	err_mess = rb_sprintf("wrong number of arguments (given %d, expected %d..%d)", argc, min, max);
     }
     return rb_exc_new3(rb_eArgError, err_mess);
 }