diff --git a/examples/client.c b/examples/client.c
index 58947fa1..c58e6ade 100644
--- a/examples/client.c
+++ b/examples/client.c
@@ -52,14 +52,12 @@ enum {
 };
 
 #define MAKE_NV(NAME, VALUE)                                            \
-  {(uint8_t*)NAME, (uint8_t*)VALUE,                                     \
-      (uint16_t)(sizeof(NAME) - 1), (uint16_t)(sizeof(VALUE) - 1),      \
-      NGHTTP2_NV_FLAG_NONE }
+  {(uint8_t*)NAME, (uint8_t*)VALUE, sizeof(NAME) - 1, sizeof(VALUE) - 1, \
+      NGHTTP2_NV_FLAG_NONE}
 
 #define MAKE_NV_CS(NAME, VALUE)                                         \
-  {(uint8_t*)NAME, (uint8_t*)VALUE,                                     \
-      (uint16_t)(sizeof(NAME) - 1), (uint16_t)(strlen(VALUE)),          \
-      NGHTTP2_NV_FLAG_NONE }
+  {(uint8_t*)NAME, (uint8_t*)VALUE, sizeof(NAME) - 1, strlen(VALUE),    \
+      NGHTTP2_NV_FLAG_NONE}
 
 struct Connection {
   SSL *ssl;
diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index e3af10ec..28fdae40 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -384,11 +384,11 @@ typedef struct {
   /**
    * The length of the |name|.
    */
-  uint16_t namelen;
+  size_t namelen;
   /**
    * The length of the |value|.
    */
-  uint16_t valuelen;
+  size_t valuelen;
   /**
    * Bitwise OR of one or more of :type:`nghttp2_nv_flag`.
    */
diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index b5b0ef01..8729cfb8 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -140,8 +140,8 @@ typedef struct {
 } nghttp2_nva_out;
 
 int nghttp2_hd_entry_init(nghttp2_hd_entry *ent, uint8_t flags,
-                          uint8_t *name, uint16_t namelen,
-                          uint8_t *value, uint16_t valuelen)
+                          uint8_t *name, size_t namelen,
+                          uint8_t *value, size_t valuelen)
 {
   int rv = 0;
 
@@ -706,7 +706,7 @@ static int emit_indname_block(nghttp2_bufs *bufs, size_t index,
   }
 
   DEBUGF(fprintf(stderr,
-                 "deflatehd: emit indname index=%zu, valuelen=%u, "
+                 "deflatehd: emit indname index=%zu, valuelen=%zu, "
                  "indexing=%d, no_index=%d\n",
                  index, nv->valuelen, inc_indexing, no_index));
 
@@ -754,7 +754,7 @@ static int emit_newname_block(nghttp2_bufs *bufs, nghttp2_nv *nv,
   no_index = (nv->flags & NGHTTP2_NV_FLAG_NO_INDEX) != 0;
 
   DEBUGF(fprintf(stderr,
-                 "deflatehd: emit newname namelen=%u, valuelen=%u, "
+                 "deflatehd: emit newname namelen=%zu, valuelen=%zu, "
                  "indexing=%d, no_index=%d\n",
                  nv->namelen, nv->valuelen, inc_indexing, no_index));
 
diff --git a/lib/nghttp2_hd.h b/lib/nghttp2_hd.h
index 31bbd57b..e87a5596 100644
--- a/lib/nghttp2_hd.h
+++ b/lib/nghttp2_hd.h
@@ -195,8 +195,8 @@ struct nghttp2_hd_inflater {
  *     Out of memory.
  */
 int nghttp2_hd_entry_init(nghttp2_hd_entry *ent, uint8_t flags,
-                          uint8_t *name, uint16_t namelen,
-                          uint8_t *value, uint16_t valuelen);
+                          uint8_t *name, size_t namelen,
+                          uint8_t *value, size_t valuelen);
 
 void nghttp2_hd_entry_free(nghttp2_hd_entry *ent);
 
diff --git a/src/app_helper.cc b/src/app_helper.cc
index 93edb5c9..5c6f81ec 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -483,7 +483,7 @@ int verbose_on_header_callback(nghttp2_session *session,
 {
   nghttp2_nv nva = {
     const_cast<uint8_t*>(name), const_cast<uint8_t*>(value),
-    static_cast<uint16_t>(namelen), static_cast<uint16_t>(valuelen)
+    namelen, valuelen
   };
 
   for(auto& nv : http2::sort_nva(&nva, 1)) {
diff --git a/src/http2.cc b/src/http2.cc
index a7655aef..1d941f71 100644
--- a/src/http2.cc
+++ b/src/http2.cc
@@ -252,7 +252,7 @@ std::vector<nghttp2_nv> sort_nva(const nghttp2_nv *nva, size_t nvlen)
         break;
       }
       auto l = std::find(j, end, '\0');
-      res.push_back({v[i].name, j, v[i].namelen, static_cast<uint16_t>(l-j)});
+      res.push_back({v[i].name, j, v[i].namelen, static_cast<size_t>(l - j)});
       j = l;
     }
   }
@@ -346,12 +346,8 @@ nghttp2_nv make_nv(const std::string& name, const std::string& value,
 
   flags = no_index ? NGHTTP2_NV_FLAG_NO_INDEX : NGHTTP2_NV_FLAG_NONE;
 
-  return {
-    (uint8_t*)name.c_str(),
-      (uint8_t*)value.c_str(),
-      (uint16_t)name.size(), (uint16_t)value.size(),
-      flags
-      };
+  return {(uint8_t*)name.c_str(), (uint8_t*)value.c_str(),
+      name.size(), value.size(), flags};
 }
 
 Headers concat_norm_headers(Headers headers)
diff --git a/src/http2.h b/src/http2.h
index eefe5552..39cb3013 100644
--- a/src/http2.h
+++ b/src/http2.h
@@ -160,18 +160,15 @@ nghttp2_nv make_nv(const std::string& name, const std::string& value,
 template<size_t N, size_t M>
 nghttp2_nv make_nv_ll(const char(&name)[N], const char(&value)[M])
 {
-  return { (uint8_t*)name, (uint8_t*)value,
-      (uint16_t)(N - 1), (uint16_t)(M - 1),
-      NGHTTP2_NV_FLAG_NONE };
+  return {(uint8_t*)name, (uint8_t*)value, N - 1, M - 1, NGHTTP2_NV_FLAG_NONE};
 }
 
 // Create nghttp2_nv from string literal |name| and c-string |value|.
 template<size_t N>
 nghttp2_nv make_nv_lc(const char(&name)[N], const char *value)
 {
-  return { (uint8_t*)name, (uint8_t*)value,
-      (uint16_t)(N - 1), (uint16_t)strlen(value),
-      NGHTTP2_NV_FLAG_NONE };
+  return {(uint8_t*)name, (uint8_t*)value, N - 1, strlen(value),
+      NGHTTP2_NV_FLAG_NONE};
 }
 
 // Create nghttp2_nv from string literal |name| and std::string
@@ -179,9 +176,8 @@ nghttp2_nv make_nv_lc(const char(&name)[N], const char *value)
 template<size_t N>
 nghttp2_nv make_nv_ls(const char(&name)[N], const std::string& value)
 {
-  return { (uint8_t*)name, (uint8_t*)value.c_str(),
-      (uint16_t)(N - 1), (uint16_t)value.size(),
-      NGHTTP2_NV_FLAG_NONE };
+  return {(uint8_t*)name, (uint8_t*)value.c_str(), N - 1, value.size(),
+      NGHTTP2_NV_FLAG_NONE};
 }
 
 // Appends headers in |headers| to |nv|. Certain headers, including
diff --git a/src/http2_test.cc b/src/http2_test.cc
index 1f957d6e..fa6dce8e 100644
--- a/src/http2_test.cc
+++ b/src/http2_test.cc
@@ -38,8 +38,8 @@
 using namespace nghttp2;
 
 #define MAKE_NV(K, V) {(uint8_t*)K, (uint8_t*)V,        \
-      (uint16_t)(sizeof(K)-1), (uint16_t)(sizeof(V)-1), \
-      NGHTTP2_NV_FLAG_NONE }
+      sizeof(K) - 1, sizeof(V) - 1,                     \
+      NGHTTP2_NV_FLAG_NONE}
 
 namespace shrpx {
 
diff --git a/tests/nghttp2_frame_test.c b/tests/nghttp2_frame_test.c
index d3384c75..7f6d2141 100644
--- a/tests/nghttp2_frame_test.c
+++ b/tests/nghttp2_frame_test.c
@@ -569,7 +569,7 @@ void test_nghttp2_nv_array_copy(void)
   nghttp2_nv bignv;
 
   bignv.name = (uint8_t*)"echo";
-  bignv.namelen = (uint16_t)strlen("echo");
+  bignv.namelen = strlen("echo");
   bignv.valuelen = (1 << 14) - 1;
   bignv.value = malloc(bignv.valuelen);
   memset(bignv.value, '0', bignv.valuelen);