diff --git a/lib/nghttp2_stream.c b/lib/nghttp2_stream.c
index e348c1ef..bc3c507f 100644
--- a/lib/nghttp2_stream.c
+++ b/lib/nghttp2_stream.c
@@ -601,10 +601,37 @@ void nghttp2_stream_dep_insert(nghttp2_stream *dep_stream,
   ++stream->roots->num_streams;
 }
 
+static void link_dep(nghttp2_stream *dep_stream, nghttp2_stream *stream)
+{
+  dep_stream->dep_next = stream;
+  stream->dep_prev = dep_stream;
+}
+
+static void link_sib(nghttp2_stream *prev_stream, nghttp2_stream *stream)
+{
+  prev_stream->sib_next = stream;
+  stream->sib_prev = prev_stream;
+}
+
+static void insert_link_dep(nghttp2_stream *dep_stream,
+                            nghttp2_stream *stream)
+{
+  nghttp2_stream *sib_next;
+
+  assert(stream->sib_prev == NULL);
+
+  sib_next = dep_stream->dep_next;
+
+  link_sib(stream, sib_next);
+
+  sib_next->dep_prev = NULL;
+
+  link_dep(dep_stream, stream);
+}
+
 void nghttp2_stream_dep_add(nghttp2_stream *dep_stream,
                             nghttp2_stream *stream)
 {
-  nghttp2_stream *last_sib;
   nghttp2_stream *root_stream;
 
   assert(stream->data_item == NULL);
@@ -622,9 +649,7 @@ void nghttp2_stream_dep_add(nghttp2_stream *dep_stream,
     dep_stream->dep_next = stream;
     stream->dep_prev = dep_stream;
   } else {
-    last_sib = stream_last_sib(dep_stream->dep_next);
-    last_sib->sib_next = stream;
-    stream->sib_prev = last_sib;
+    insert_link_dep(dep_stream, stream);
   }
 
   stream_update_dep_sum_norest_weight(root_stream);
@@ -813,7 +838,6 @@ int nghttp2_stream_dep_add_subtree(nghttp2_stream *dep_stream,
                                    nghttp2_pq *pq,
                                    uint64_t cycle)
 {
-  nghttp2_stream *last_sib;
   nghttp2_stream *root_stream;
 
   DEBUGF(fprintf(stderr, "stream: dep_add_subtree dep_stream(%p)=%d "
@@ -826,10 +850,7 @@ int nghttp2_stream_dep_add_subtree(nghttp2_stream *dep_stream,
   if(dep_stream->dep_next) {
     dep_stream->sum_dep_weight += stream->weight;
 
-    last_sib = stream_last_sib(dep_stream->dep_next);
-
-    last_sib->sib_next = stream;
-    stream->sib_prev = last_sib;
+    insert_link_dep(dep_stream, stream);
   } else {
     dep_stream->dep_next = stream;
     stream->dep_prev = dep_stream;
@@ -961,12 +982,14 @@ int nghttp2_stream_dep_all_your_stream_are_belong_to_us
     }
 
     if(stream->dep_next) {
-      nghttp2_stream *last_sib;
+      nghttp2_stream *sib_next;
 
-      last_sib = stream_last_sib(stream->dep_next);
+      sib_next = stream->dep_next;
 
-      last_sib->sib_next = first;
-      first->sib_prev = last_sib;
+      sib_next->dep_prev = NULL;
+
+      link_sib(first, sib_next);
+      link_dep(stream, prev);
     } else {
       stream->dep_next = first;
       first->dep_prev = stream;
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 218fba42..5195d957 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -5339,8 +5339,8 @@ void test_nghttp2_session_stream_dep_add(void)
 
   a = open_stream(session, 1);
 
-  b = open_stream_with_dep(session, 3, a);
   c = open_stream_with_dep(session, 5, a);
+  b = open_stream_with_dep(session, 3, a);
   d = open_stream_with_dep(session, 7, c);
 
   /* a
@@ -5423,9 +5423,9 @@ void test_nghttp2_session_stream_dep_remove(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   nghttp2_stream_dep_remove(a);
@@ -5452,9 +5452,9 @@ void test_nghttp2_session_stream_dep_remove(void)
   check_stream_dep_sib(d, c, NULL, NULL, NULL);
 
   CU_ASSERT(3 == session->roots.num_streams);
-  CU_ASSERT(c == session->roots.head);
-  CU_ASSERT(b == c->root_next);
-  CU_ASSERT(NULL == b->root_next);
+  CU_ASSERT(b == session->roots.head);
+  CU_ASSERT(c == b->root_next);
+  CU_ASSERT(NULL == c->root_next);
 
   nghttp2_session_del(session);
 
@@ -5468,9 +5468,9 @@ void test_nghttp2_session_stream_dep_remove(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   nghttp2_stream_dep_remove(b);
@@ -5514,9 +5514,9 @@ void test_nghttp2_session_stream_dep_remove(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   nghttp2_stream_dep_remove(c);
@@ -5524,7 +5524,7 @@ void test_nghttp2_session_stream_dep_remove(void)
   /* becomes:
    * a
    * |
-   * b--d
+   * d--b
    */
 
   CU_ASSERT(3 == a->num_substreams);
@@ -5537,10 +5537,10 @@ void test_nghttp2_session_stream_dep_remove(void)
   CU_ASSERT(0 == d->sum_dep_weight);
   CU_ASSERT(0 == c->sum_dep_weight);
 
-  check_stream_dep_sib(a, NULL, b, NULL, NULL);
-  check_stream_dep_sib(b, a, NULL, NULL, d);
+  check_stream_dep_sib(a, NULL, d, NULL, NULL);
+  check_stream_dep_sib(b, NULL, NULL, d, NULL);
   check_stream_dep_sib(c, NULL, NULL, NULL, NULL);
-  check_stream_dep_sib(d, NULL, NULL, b, NULL);
+  check_stream_dep_sib(d, a, NULL, NULL, b);
 
   nghttp2_session_del(session);
 
@@ -5556,9 +5556,9 @@ void test_nghttp2_session_stream_dep_remove(void)
 
   /* a
    * |
-   * b--c--d
+   * d--c--b
    *    |
-   *    e--f
+   *    f--e
    */
 
   CU_ASSERT(6 == a->num_substreams);
@@ -5580,7 +5580,7 @@ void test_nghttp2_session_stream_dep_remove(void)
   /* becomes:
    * a
    * |
-   * b--e--f--d
+   * d--f--e--b
    */
 
   CU_ASSERT(5 == a->num_substreams);
@@ -5599,12 +5599,12 @@ void test_nghttp2_session_stream_dep_remove(void)
   CU_ASSERT(0 == e->sum_dep_weight);
   CU_ASSERT(0 == f->sum_dep_weight);
 
-  check_stream_dep_sib(a, NULL, b, NULL, NULL);
-  check_stream_dep_sib(b, a, NULL, NULL, e);
+  check_stream_dep_sib(a, NULL, d, NULL, NULL);
+  check_stream_dep_sib(b, NULL, NULL, e, NULL);
   check_stream_dep_sib(c, NULL, NULL, NULL, NULL);
-  check_stream_dep_sib(e, NULL, NULL, b, f);
-  check_stream_dep_sib(f, NULL, NULL, e, d);
-  check_stream_dep_sib(d, NULL, NULL, f, NULL);
+  check_stream_dep_sib(e, NULL, NULL, f, b);
+  check_stream_dep_sib(f, NULL, NULL, d, e);
+  check_stream_dep_sib(d, a, NULL, NULL, f);
 
   nghttp2_session_del(session);
 }
@@ -5630,9 +5630,9 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
 
   /* a         e
    * |         |
-   * b--c      f
-   *    |
-   *    d
+   * c--b      f
+   * |
+   * d
    */
 
   nghttp2_stream_dep_add_subtree(a, e, &session->ob_da_pq,
@@ -5641,9 +5641,9 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
   /* becomes
    * a
    * |
-   * b--c--e
-   *    |  |
-   *    d  f
+   * e--c--b
+   * |  |
+   * f  d
    */
 
   CU_ASSERT(6 == a->num_substreams);
@@ -5660,11 +5660,11 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
   CU_ASSERT(NGHTTP2_DEFAULT_WEIGHT == e->sum_dep_weight);
   CU_ASSERT(0 == f->sum_dep_weight);
 
-  check_stream_dep_sib(a, NULL, b, NULL, NULL);
-  check_stream_dep_sib(b, a, NULL, NULL, c);
-  check_stream_dep_sib(c, NULL, d, b, e);
+  check_stream_dep_sib(a, NULL, e, NULL, NULL);
+  check_stream_dep_sib(b, NULL, NULL, c, NULL);
+  check_stream_dep_sib(c, NULL, d, e, b);
   check_stream_dep_sib(d, c, NULL, NULL, NULL);
-  check_stream_dep_sib(e, NULL, f, c, NULL);
+  check_stream_dep_sib(e, a, f, NULL, c);
   check_stream_dep_sib(f, e, NULL, NULL, NULL);
 
   nghttp2_session_del(session);
@@ -5682,9 +5682,9 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
 
   /* a         e
    * |         |
-   * b--c      f
-   *    |
-   *    d
+   * c--b      f
+   * |
+   * d
    */
 
   nghttp2_stream_dep_insert_subtree(a, e, &session->ob_da_pq,
@@ -5695,9 +5695,9 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
    * |
    * e
    * |
-   * f--b--c
-   *       |
-   *       d
+   * f--c--b
+   *    |
+   *    d
    */
 
   CU_ASSERT(6 == a->num_substreams);
@@ -5716,9 +5716,9 @@ void test_nghttp2_session_stream_dep_add_subtree(void)
 
   check_stream_dep_sib(a, NULL, e, NULL, NULL);
   check_stream_dep_sib(e, a, f, NULL, NULL);
-  check_stream_dep_sib(f, e, NULL, NULL, b);
-  check_stream_dep_sib(b, NULL, NULL, f, c);
-  check_stream_dep_sib(c, NULL, d, b, NULL);
+  check_stream_dep_sib(f, e, NULL, NULL, c);
+  check_stream_dep_sib(b, NULL, NULL, c, NULL);
+  check_stream_dep_sib(c, NULL, d, f, b);
   check_stream_dep_sib(d, c, NULL, NULL, NULL);
 
   nghttp2_session_del(session);
@@ -5742,9 +5742,9 @@ void test_nghttp2_session_stream_dep_remove_subtree(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   nghttp2_stream_dep_remove_subtree(c);
@@ -5782,9 +5782,9 @@ void test_nghttp2_session_stream_dep_remove_subtree(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   nghttp2_stream_dep_remove_subtree(b);
@@ -5818,10 +5818,10 @@ void test_nghttp2_session_stream_dep_remove_subtree(void)
   nghttp2_session_server_new(&session, &callbacks, NULL);
 
   a = open_stream(session, 1);
-  b = open_stream_with_dep(session, 3, a);
-  c = open_stream_with_dep(session, 5, a);
-  d = open_stream_with_dep(session, 7, c);
   e = open_stream_with_dep(session, 9, a);
+  c = open_stream_with_dep(session, 5, a);
+  b = open_stream_with_dep(session, 3, a);
+  d = open_stream_with_dep(session, 7, c);
 
   /* a
    * |
@@ -5961,9 +5961,9 @@ void test_nghttp2_session_stream_dep_all_your_stream_are_belong_to_us(void)
   /*
    * c
    * |
-   * d--a
-   *    |
-   *    b
+   * a--d
+   * |
+   * b
    */
 
   CU_ASSERT(4 == c->num_substreams);
@@ -5976,9 +5976,9 @@ void test_nghttp2_session_stream_dep_all_your_stream_are_belong_to_us(void)
   CU_ASSERT(NGHTTP2_DEFAULT_WEIGHT == a->sum_dep_weight);
   CU_ASSERT(0 == b->sum_dep_weight);
 
-  check_stream_dep_sib(c, NULL, d, NULL, NULL);
-  check_stream_dep_sib(d, c, NULL, NULL, a);
-  check_stream_dep_sib(a, NULL, b, d, NULL);
+  check_stream_dep_sib(c, NULL, a, NULL, NULL);
+  check_stream_dep_sib(d, NULL, NULL, a, NULL);
+  check_stream_dep_sib(a, c, b, NULL, d);
   check_stream_dep_sib(b, a, NULL, NULL, NULL);
 
   nghttp2_session_del(session);
@@ -6002,9 +6002,9 @@ void test_nghttp2_session_stream_attach_data(void)
 
   /* a
    * |
-   * b--c
-   *    |
-   *    d
+   * c--b
+   * |
+   * d
    */
 
   db = create_data_ob_item();
@@ -6121,9 +6121,9 @@ void test_nghttp2_session_stream_attach_data_subtree(void)
   /*
    * a        e
    * |        |
-   * b--c     f
-   *    |
-   *    d
+   * c--b     f
+   * |
+   * d
    */
 
   de = create_data_ob_item();
@@ -6155,9 +6155,9 @@ void test_nghttp2_session_stream_attach_data_subtree(void)
    * |
    * e
    * |
-   * f--b--c
-   *       |
-   *       d
+   * f--c--b
+   *    |
+   *    d
    */
 
   CU_ASSERT(NGHTTP2_STREAM_DPRI_NO_DATA == a->dpri);
@@ -6242,9 +6242,9 @@ void test_nghttp2_session_stream_attach_data_subtree(void)
   /*
    * a       b
    * |
-   * e--c
+   * c--e
    * |  |
-   * f  d
+   * d  f
    */
 
   CU_ASSERT(NGHTTP2_STREAM_DPRI_NO_DATA == a->dpri);