diff --git a/lib/nghttp2_outbound_item.c b/lib/nghttp2_outbound_item.c
index 9450ad7c..1633cc36 100644
--- a/lib/nghttp2_outbound_item.c
+++ b/lib/nghttp2_outbound_item.c
@@ -90,8 +90,6 @@ void nghttp2_outbound_item_free(nghttp2_outbound_item *item, nghttp2_mem *mem) {
       assert(0);
       break;
     }
-
-    nghttp2_mem_free(mem, frame->ext.payload);
   }
   }
 }
diff --git a/lib/nghttp2_outbound_item.h b/lib/nghttp2_outbound_item.h
index ce458a3a..8bda776b 100644
--- a/lib/nghttp2_outbound_item.h
+++ b/lib/nghttp2_outbound_item.h
@@ -107,6 +107,9 @@ typedef struct nghttp2_outbound_item nghttp2_outbound_item;
 
 struct nghttp2_outbound_item {
   nghttp2_frame frame;
+  /* Storage for extension frame payload.  frame->ext.payload points
+     to this structure to avoid frequent memory allocation. */
+  nghttp2_ext_frame_payload ext_frame_payload;
   nghttp2_aux_data aux_data;
   /* The priority used in priority comparion.  Smaller is served
      ealier.  For PING, SETTINGS and non-DATA frames (excluding
diff --git a/lib/nghttp2_submit.c b/lib/nghttp2_submit.c
index 4aa19470..6329334c 100644
--- a/lib/nghttp2_submit.c
+++ b/lib/nghttp2_submit.c
@@ -470,11 +470,7 @@ int nghttp2_submit_altsvc(nghttp2_session *session, uint8_t flags _U_,
 
   item->aux_data.ext.builtin = 1;
 
-  altsvc = nghttp2_mem_malloc(mem, sizeof(nghttp2_ext_altsvc));
-  if (altsvc == NULL) {
-    rv = NGHTTP2_ERR_NOMEM;
-    goto fail_altsvc_malloc;
-  }
+  altsvc = &item->ext_frame_payload.altsvc;
 
   frame = &item->frame;
   frame->ext.payload = altsvc;
@@ -485,7 +481,6 @@ int nghttp2_submit_altsvc(nghttp2_session *session, uint8_t flags _U_,
   rv = nghttp2_session_add_item(session, item);
   if (rv != 0) {
     nghttp2_frame_altsvc_free(&frame->ext, mem);
-    nghttp2_mem_free(mem, frame->ext.payload);
     nghttp2_mem_free(mem, item);
 
     return rv;
@@ -493,8 +488,6 @@ int nghttp2_submit_altsvc(nghttp2_session *session, uint8_t flags _U_,
 
   return 0;
 
-fail_altsvc_malloc:
-  free(item);
 fail_item_malloc:
   free(buf);