diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 8c54b9c8..a5dc10dd 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -1747,8 +1747,8 @@ typedef int (*nghttp2_on_header_callback)(nghttp2_session *session,
  */
 typedef int (*nghttp2_on_header_callback2)(nghttp2_session *session,
                                            const nghttp2_frame *frame,
-                                           nghttp2_rcbuf *name,
-                                           nghttp2_rcbuf *value, uint8_t flags,
+                                           const nghttp2_rcbuf *name,
+                                           const nghttp2_rcbuf *value, uint8_t flags,
                                            void *user_data);
 
 /**
@@ -1815,8 +1815,8 @@ typedef int (*nghttp2_on_invalid_header_callback)(
  * :enum:`NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_on_invalid_header_callback2)(
-    nghttp2_session *session, const nghttp2_frame *frame, nghttp2_rcbuf *name,
-    nghttp2_rcbuf *value, uint8_t flags, void *user_data);
+    nghttp2_session *session, const nghttp2_frame *frame, const nghttp2_rcbuf *name,
+    const nghttp2_rcbuf *value, uint8_t flags, void *user_data);
 
 /**
  * @functypedef
diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index 82cc23de..e6d605bf 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -1290,8 +1290,7 @@ nghttp2_hd_nv nghttp2_hd_table_get(nghttp2_hd_context *context, size_t idx) {
         ->nv;
   } else {
     const nghttp2_hd_static_entry *ent = &static_table[idx];
-    nghttp2_hd_nv nv = {(nghttp2_rcbuf *)&ent->name,
-                        (nghttp2_rcbuf *)&ent->value, ent->token,
+    nghttp2_hd_nv nv = {&ent->name, &ent->value, ent->token,
                         NGHTTP2_NV_FLAG_NONE};
     return nv;
   }
diff --git a/lib/nghttp2_hd.h b/lib/nghttp2_hd.h
index c64a1f2b..96081d13 100644
--- a/lib/nghttp2_hd.h
+++ b/lib/nghttp2_hd.h
@@ -119,10 +119,10 @@ typedef struct nghttp2_hd_entry nghttp2_hd_entry;
 typedef struct {
   /* The buffer containing header field name.  NULL-termination is
      guaranteed. */
-  nghttp2_rcbuf *name;
+  const nghttp2_rcbuf *name;
   /* The buffer containing header field value.  NULL-termination is
      guaranteed. */
-  nghttp2_rcbuf *value;
+  const nghttp2_rcbuf *value;
   /* nghttp2_token value for name.  It could be -1 if we have no token
      for that header field name. */
   int32_t token;
@@ -236,7 +236,7 @@ struct nghttp2_hd_inflater {
   nghttp2_rcbuf *namercbuf, *valuercbuf;
   /* Pointer to the name/value pair which are used in the current
      header emission. */
-  nghttp2_rcbuf *nv_name_keep, *nv_value_keep;
+  const nghttp2_rcbuf *nv_name_keep, *nv_value_keep;
   /* The number of bytes to read */
   size_t left;
   /* The index in indexed repr or indexed name */