diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index 4009ea74..71bdbfa3 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -737,46 +737,44 @@ int on_stream_close_callback(nghttp2_session *session, int32_t stream_id,
   auto dconn = sd->dconn;
   if (dconn) {
     auto downstream = dconn->get_downstream();
-    if (downstream) {
-      auto upstream = downstream->get_upstream();
+    auto upstream = downstream->get_upstream();
 
-      if (downstream->get_downstream_stream_id() % 2 == 0 &&
-          downstream->get_request_state() == Downstream::INITIAL) {
-        // Downstream is canceled in backend before it is submitted in
-        // frontend session.
+    if (downstream->get_downstream_stream_id() % 2 == 0 &&
+        downstream->get_request_state() == Downstream::INITIAL) {
+      // Downstream is canceled in backend before it is submitted in
+      // frontend session.
 
-        // This will avoid to send RST_STREAM to backend
-        downstream->set_response_state(Downstream::MSG_RESET);
-        upstream->cancel_premature_downstream(downstream);
-      } else {
-        if (downstream->get_upgraded() &&
-            downstream->get_response_state() == Downstream::HEADER_COMPLETE) {
-          // For tunneled connection, we have to submit RST_STREAM to
-          // upstream *after* whole response body is sent. We just set
-          // MSG_COMPLETE here. Upstream will take care of that.
-          downstream->get_upstream()->on_downstream_body_complete(downstream);
-          downstream->set_response_state(Downstream::MSG_COMPLETE);
-        } else if (error_code == NGHTTP2_NO_ERROR) {
-          switch (downstream->get_response_state()) {
-          case Downstream::MSG_COMPLETE:
-          case Downstream::MSG_BAD_HEADER:
-            break;
-          default:
-            downstream->set_response_state(Downstream::MSG_RESET);
-          }
-        } else if (downstream->get_response_state() !=
-                   Downstream::MSG_BAD_HEADER) {
+      // This will avoid to send RST_STREAM to backend
+      downstream->set_response_state(Downstream::MSG_RESET);
+      upstream->cancel_premature_downstream(downstream);
+    } else {
+      if (downstream->get_upgraded() &&
+          downstream->get_response_state() == Downstream::HEADER_COMPLETE) {
+        // For tunneled connection, we have to submit RST_STREAM to
+        // upstream *after* whole response body is sent. We just set
+        // MSG_COMPLETE here. Upstream will take care of that.
+        downstream->get_upstream()->on_downstream_body_complete(downstream);
+        downstream->set_response_state(Downstream::MSG_COMPLETE);
+      } else if (error_code == NGHTTP2_NO_ERROR) {
+        switch (downstream->get_response_state()) {
+        case Downstream::MSG_COMPLETE:
+        case Downstream::MSG_BAD_HEADER:
+          break;
+        default:
           downstream->set_response_state(Downstream::MSG_RESET);
         }
-        if (downstream->get_response_state() == Downstream::MSG_RESET &&
-            downstream->get_response_rst_stream_error_code() ==
-                NGHTTP2_NO_ERROR) {
-          downstream->set_response_rst_stream_error_code(error_code);
-        }
-        call_downstream_readcb(http2session, downstream);
+      } else if (downstream->get_response_state() !=
+                 Downstream::MSG_BAD_HEADER) {
+        downstream->set_response_state(Downstream::MSG_RESET);
       }
-      // dconn may be deleted
+      if (downstream->get_response_state() == Downstream::MSG_RESET &&
+          downstream->get_response_rst_stream_error_code() ==
+              NGHTTP2_NO_ERROR) {
+        downstream->set_response_rst_stream_error_code(error_code);
+      }
+      call_downstream_readcb(http2session, downstream);
     }
+    // dconn may be deleted
   }
   // The life time of StreamData ends here
   http2session->remove_stream_data(sd);
@@ -806,9 +804,6 @@ int on_header_callback2(nghttp2_session *session, const nghttp2_frame *frame,
     return 0;
   }
   auto downstream = sd->dconn->get_downstream();
-  if (!downstream) {
-    return 0;
-  }
 
   auto namebuf = nghttp2_rcbuf_get_buf(name);
   auto valuebuf = nghttp2_rcbuf_get_buf(value);
@@ -918,10 +913,6 @@ int on_invalid_header_callback2(nghttp2_session *session,
   if (!sd || !sd->dconn) {
     return 0;
   }
-  auto downstream = sd->dconn->get_downstream();
-  if (!downstream) {
-    return 0;
-  }
 
   int32_t stream_id;
 
@@ -966,12 +957,6 @@ int on_begin_headers_callback(nghttp2_session *session,
                                       NGHTTP2_INTERNAL_ERROR);
       return 0;
     }
-    auto downstream = sd->dconn->get_downstream();
-    if (!downstream) {
-      http2session->submit_rst_stream(frame->hd.stream_id,
-                                      NGHTTP2_INTERNAL_ERROR);
-      return 0;
-    }
     return 0;
   }
   case NGHTTP2_PUSH_PROMISE: {
@@ -1132,10 +1117,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
       return 0;
     }
     auto downstream = sd->dconn->get_downstream();
-    if (!downstream) {
-      return 0;
-    }
-
     auto upstream = downstream->get_upstream();
     rv = upstream->on_downstream_body(downstream, nullptr, 0, true);
     if (rv != 0) {
@@ -1170,10 +1151,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
     }
     auto downstream = sd->dconn->get_downstream();
 
-    if (!downstream) {
-      return 0;
-    }
-
     if (frame->headers.cat == NGHTTP2_HCAT_RESPONSE ||
         frame->headers.cat == NGHTTP2_HCAT_PUSH_RESPONSE) {
       rv = on_response_headers(http2session, downstream, session, frame);
@@ -1219,11 +1196,9 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
         nghttp2_session_get_stream_user_data(session, frame->hd.stream_id));
     if (sd && sd->dconn) {
       auto downstream = sd->dconn->get_downstream();
-      if (downstream) {
-        downstream->set_response_rst_stream_error_code(
-            frame->rst_stream.error_code);
-        call_downstream_readcb(http2session, downstream);
-      }
+      downstream->set_response_rst_stream_error_code(
+          frame->rst_stream.error_code);
+      call_downstream_readcb(http2session, downstream);
     }
     return 0;
   }
@@ -1325,7 +1300,7 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
     return 0;
   }
   auto downstream = sd->dconn->get_downstream();
-  if (!downstream || !downstream->expect_response_body()) {
+  if (!downstream->expect_response_body()) {
     http2session->submit_rst_stream(stream_id, NGHTTP2_INTERNAL_ERROR);
 
     if (http2session->consume(stream_id, len) != 0) {
@@ -1386,10 +1361,6 @@ int on_frame_send_callback(nghttp2_session *session, const nghttp2_frame *frame,
 
     auto downstream = sd->dconn->get_downstream();
 
-    if (!downstream) {
-      return 0;
-    }
-
     if (frame->hd.type == NGHTTP2_HEADERS &&
         frame->headers.cat == NGHTTP2_HCAT_REQUEST) {
       downstream->set_request_header_sent(true);
@@ -1438,9 +1409,6 @@ int on_frame_not_send_callback(nghttp2_session *session,
     return 0;
   }
   auto downstream = sd->dconn->get_downstream();
-  if (!downstream) {
-    return 0;
-  }
 
   if (lib_error_code == NGHTTP2_ERR_START_STREAM_NOT_ALLOWED) {
     // Migrate to another downstream connection.
@@ -1829,7 +1797,7 @@ void Http2Session::submit_pending_requests() {
   for (auto dconn = dconns_.head; dconn; dconn = dconn->dlnext) {
     auto downstream = dconn->get_downstream();
 
-    if (!downstream || !downstream->get_request_pending() ||
+    if (!downstream->get_request_pending() ||
         !downstream->request_submission_ready()) {
       continue;
     }