diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index d41d5699..b420c983 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -1708,8 +1708,14 @@ static int nghttp2_session_prep_frame(nghttp2_session *session,
     next_readmax = nghttp2_session_next_data_read(session, stream);
 
     if(next_readmax == 0) {
-      nghttp2_stream_defer_data(stream,
-                                NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL);
+      rv = nghttp2_stream_defer_data(stream,
+                                     NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL,
+                                     &session->ob_pq);
+
+      if(nghttp2_is_fatal(rv)) {
+        return rv;
+      }
+
       session->aob.item = NULL;
       nghttp2_active_outbound_item_reset(&session->aob);
       return NGHTTP2_ERR_DEFERRED;
@@ -1719,7 +1725,13 @@ static int nghttp2_session_prep_frame(nghttp2_session *session,
                                         next_readmax,
                                         data_frame);
     if(framerv == NGHTTP2_ERR_DEFERRED) {
-      nghttp2_stream_defer_data(stream, NGHTTP2_STREAM_FLAG_DEFERRED_USER);
+      rv = nghttp2_stream_defer_data(stream, NGHTTP2_STREAM_FLAG_DEFERRED_USER,
+                                     &session->ob_pq);
+
+      if(nghttp2_is_fatal(rv)) {
+        return rv;
+      }
+
       session->aob.item = NULL;
       nghttp2_active_outbound_item_reset(&session->aob);
       return NGHTTP2_ERR_DEFERRED;
@@ -2107,8 +2119,13 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
       next_readmax = nghttp2_session_next_data_read(session, stream);
 
       if(next_readmax == 0) {
-        nghttp2_stream_defer_data(stream,
-                                  NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL);
+        rv = nghttp2_stream_defer_data
+          (stream, NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL, &session->ob_pq);
+
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        }
+
         aob->item = NULL;
         nghttp2_active_outbound_item_reset(aob);
 
@@ -2123,7 +2140,14 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
         return rv;
       }
       if(rv == NGHTTP2_ERR_DEFERRED) {
-        nghttp2_stream_defer_data(stream, NGHTTP2_STREAM_FLAG_DEFERRED_USER);
+        rv = nghttp2_stream_defer_data(stream,
+                                       NGHTTP2_STREAM_FLAG_DEFERRED_USER,
+                                       &session->ob_pq);
+
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        }
+
         aob->item = NULL;
         nghttp2_active_outbound_item_reset(aob);
 
diff --git a/lib/nghttp2_stream.c b/lib/nghttp2_stream.c
index c9883877..ecd067ff 100644
--- a/lib/nghttp2_stream.c
+++ b/lib/nghttp2_stream.c
@@ -359,11 +359,17 @@ int nghttp2_stream_detach_data(nghttp2_stream *stream, nghttp2_pq *pq)
   return stream_update_dep_on_detach_data(stream, pq);
 }
 
-void nghttp2_stream_defer_data(nghttp2_stream *stream, uint8_t flags)
+int nghttp2_stream_defer_data(nghttp2_stream *stream, uint8_t flags,
+                              nghttp2_pq *pq)
 {
   assert(stream->data_item);
 
+  DEBUGF(fprintf(stderr, "stream: stream=%d defer data=%p cause=%02x\n",
+                 stream->stream_id, stream->data_item, flags));
+
   stream->flags |= flags;
+
+  return stream_update_dep_on_detach_data(stream, pq);
 }
 
 int nghttp2_stream_resume_deferred_data(nghttp2_stream *stream,
diff --git a/lib/nghttp2_stream.h b/lib/nghttp2_stream.h
index 9fa6e56f..eb30c2fd 100644
--- a/lib/nghttp2_stream.h
+++ b/lib/nghttp2_stream.h
@@ -185,8 +185,15 @@ void nghttp2_stream_shutdown(nghttp2_stream *stream, nghttp2_shut_flag flag);
  * bitwise OR of zero or more of NGHTTP2_STREAM_FLAG_DEFERRED_USER and
  * NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL.  The |flags| indicates
  * the reason of this action.
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_NOMEM
+ *     Out of memory
  */
-void nghttp2_stream_defer_data(nghttp2_stream *stream, uint8_t flags);
+int nghttp2_stream_defer_data(nghttp2_stream *stream, uint8_t flags,
+                              nghttp2_pq *pq);
 
 /*
  * Detaches deferred data in this stream and it is back to active
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 20ec06d6..0fc461d3 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -2201,7 +2201,9 @@ void test_nghttp2_session_on_window_update_received(void)
   CU_ASSERT(1 == user_data.frame_recv_cb_called);
   CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE+16*1024 == stream->remote_window_size);
 
-  nghttp2_stream_defer_data(stream, NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL);
+  CU_ASSERT(0 == nghttp2_stream_defer_data
+            (stream, NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL,
+             &session->ob_pq));
 
   CU_ASSERT(0 == nghttp2_session_on_window_update_received(session, &frame));
   CU_ASSERT(2 == user_data.frame_recv_cb_called);