diff --git a/struct.c b/struct.c
index 9d89134392..0afc0a9774 100644
--- a/struct.c
+++ b/struct.c
@@ -148,16 +148,19 @@ rb_struct_modify(VALUE s)
 static VALUE
 rb_struct_set(VALUE obj, VALUE val)
 {
-    VALUE members, slot;
+    VALUE members, slot, fsym;
     long i, len;
     ID fid = rb_frame_this_func();
 
     members = rb_struct_members(obj);
     len = RARRAY_LEN(members);
     rb_struct_modify(obj);
+    fid = rb_id_attrget(fid);
+    if (!fid) not_a_member(rb_frame_this_func());
+    fsym = ID2SYM(fid);
     for (i=0; i<len; i++) {
 	slot = RARRAY_AREF(members, i);
-	if (rb_id_attrset(SYM2ID(slot)) == fid) {
+	if (slot == fsym) {
 	    RSTRUCT_SET(obj, i, val);
 	    return val;
 	}
@@ -715,17 +718,17 @@ rb_struct_init_copy(VALUE copy, VALUE s)
 }
 
 static VALUE
-rb_struct_aref_id(VALUE s, ID id)
+rb_struct_aref_sym(VALUE s, VALUE name)
 {
     VALUE members = rb_struct_members(s);
     long i, len = RARRAY_LEN(members);
 
     for (i=0; i<len; i++) {
-	if (SYM2ID(RARRAY_AREF(members, i)) == id) {
+	if (RARRAY_AREF(members, i) == name) {
 	    return RSTRUCT_GET(s, i);
 	}
     }
-    rb_name_error(id, "no member '%s' in struct", rb_id2name(id));
+    rb_name_error_str(name, "no member '% "PRIsVALUE"' in struct", name);
 
     UNREACHABLE;
 }
@@ -753,7 +756,7 @@ rb_struct_aref(VALUE s, VALUE idx)
     long i;
 
     if (RB_TYPE_P(idx, T_SYMBOL)) {
-	return rb_struct_aref_id(s, SYM2ID(idx));
+	return rb_struct_aref_sym(s, idx);
     }
     else if (RB_TYPE_P(idx, T_STRING)) {
 	ID id = rb_check_id_without_pindown(&idx);
@@ -761,7 +764,7 @@ rb_struct_aref(VALUE s, VALUE idx)
 	    rb_name_error_str(idx, "no member '%"PRIsVALUE"' in struct",
 			      QUOTE(idx));
 	}
-	return rb_struct_aref_id(s, id);
+	return rb_struct_aref_sym(s, ID2SYM(id));
     }
 
     i = NUM2LONG(idx);
@@ -776,7 +779,7 @@ rb_struct_aref(VALUE s, VALUE idx)
 }
 
 static VALUE
-rb_struct_aset_id(VALUE s, ID id, VALUE val)
+rb_struct_aset_sym(VALUE s, VALUE name, VALUE val)
 {
     VALUE members = rb_struct_members(s);
     long i, len = RARRAY_LEN(members);
@@ -787,13 +790,13 @@ rb_struct_aset_id(VALUE s, ID id, VALUE val)
     }
 
     for (i=0; i<len; i++) {
-	if (SYM2ID(RARRAY_AREF(members, i)) == id) {
+	if (RARRAY_AREF(members, i) == name) {
 	    rb_struct_modify(s);
 	    RSTRUCT_SET(s, i, val);
 	    return val;
 	}
     }
-    rb_name_error(id, "no member '%s' in struct", rb_id2name(id));
+    rb_name_error_str(name, "no member '% "PRIsVALUE"' in struct", name);
 
     UNREACHABLE;
 }
@@ -823,7 +826,7 @@ rb_struct_aset(VALUE s, VALUE idx, VALUE val)
     long i;
 
     if (RB_TYPE_P(idx, T_SYMBOL)) {
-	return rb_struct_aset_id(s, SYM2ID(idx), val);
+	return rb_struct_aset_sym(s, idx, val);
     }
     if (RB_TYPE_P(idx, T_STRING)) {
 	ID id = rb_check_id(&idx);
@@ -831,7 +834,7 @@ rb_struct_aset(VALUE s, VALUE idx, VALUE val)
 	    rb_name_error_str(idx, "no member '%"PRIsVALUE"' in struct",
 			      QUOTE(idx));
 	}
-	return rb_struct_aset_id(s, id, val);
+	return rb_struct_aset_sym(s, ID2SYM(id), val);
     }
 
     i = NUM2LONG(idx);
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index 2acec57808..37366c317e 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -158,6 +158,8 @@ module TestStruct
     assert_equal(1, o[0])
     assert_raise(IndexError) { o[-2] }
     assert_raise(IndexError) { o[1] }
+    assert_raise_with_message(NameError, /foo/) {o["foo"]}
+    assert_raise_with_message(NameError, /foo/) {o[:foo]}
   end
 
   def test_aset
@@ -167,6 +169,8 @@ module TestStruct
     assert_equal(2, o[:a])
     assert_raise(IndexError) { o[-2] = 3 }
     assert_raise(IndexError) { o[1] = 3 }
+    assert_raise_with_message(NameError, /foo/) {o["foo"] = 3}
+    assert_raise_with_message(NameError, /foo/) {o[:foo] = 3}
   end
 
   def test_values_at