diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index e5f9569a..a3a53f85 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -476,10 +476,6 @@ typedef enum {
    * The ACK flag.
    */
   NGHTTP2_FLAG_ACK = 0x01,
-  /**
-   * The END_SEGMENT flag.
-   */
-  NGHTTP2_FLAG_END_SEGMENT = 0x02,
   /**
    * The PADDED flag.
    */
@@ -2382,8 +2378,7 @@ int32_t nghttp2_submit_headers(nghttp2_session *session, uint8_t flags,
  * Submits one or more DATA frames to the stream |stream_id|.  The
  * data to be sent are provided by |data_prd|.  If |flags| contains
  * :enum:`NGHTTP2_FLAG_END_STREAM`, the last DATA frame has END_STREAM
- * flag set.  If |flags| contains :enum:`NGHTTP2_FLAG_END_SEGMENT`,
- * the last DATA frame has END_SEGMENT flag set.
+ * flag set.
  *
  * This function does not take ownership of the |data_prd|.  The
  * function copies the members of the |data_prd|.
diff --git a/lib/nghttp2_frame.c b/lib/nghttp2_frame.c
index fb2f961a..228284f7 100644
--- a/lib/nghttp2_frame.c
+++ b/lib/nghttp2_frame.c
@@ -231,11 +231,10 @@ void nghttp2_frame_data_init(nghttp2_data *frame, nghttp2_private_data *pdata)
 {
   frame->hd = pdata->hd;
   frame->padlen = pdata->padlen;
-  /* flags may have NGHTTP2_FLAG_END_STREAM or
-     NGHTTP2_FLAG_END_SEGMENT even if the sent chunk is not the end of
-     the stream */
+  /* flags may have NGHTTP2_FLAG_END_STREAM even if the sent chunk is
+     not the end of the stream */
   if(!pdata->eof) {
-    frame->hd.flags &= ~(NGHTTP2_FLAG_END_STREAM | NGHTTP2_FLAG_END_SEGMENT);
+    frame->hd.flags &= ~NGHTTP2_FLAG_END_STREAM;
   }
 }
 
diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index d6e1d1d4..cd7c1df6 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -4325,7 +4325,6 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
         DEBUGF(fprintf(stderr, "recv: DATA\n"));
 
         iframe->frame.hd.flags &= (NGHTTP2_FLAG_END_STREAM |
-                                   NGHTTP2_FLAG_END_SEGMENT |
                                    NGHTTP2_FLAG_PADDED);
         /* Check stream is open. If it is not open or closing,
            ignore payload. */
@@ -4369,7 +4368,6 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
         DEBUGF(fprintf(stderr, "recv: HEADERS\n"));
 
         iframe->frame.hd.flags &= (NGHTTP2_FLAG_END_STREAM |
-                                   NGHTTP2_FLAG_END_SEGMENT |
                                    NGHTTP2_FLAG_END_HEADERS |
                                    NGHTTP2_FLAG_PADDED |
                                    NGHTTP2_FLAG_PRIORITY);
@@ -5576,7 +5574,7 @@ int nghttp2_session_pack_data(nghttp2_session *session,
 
   /* Clear flags, because this may contain previous flags of previous
      DATA */
-  frame->hd.flags &= (NGHTTP2_FLAG_END_STREAM | NGHTTP2_FLAG_END_SEGMENT);
+  frame->hd.flags &= NGHTTP2_FLAG_END_STREAM;
   flags = NGHTTP2_FLAG_NONE;
 
   if(data_flags & NGHTTP2_DATA_FLAG_EOF) {
@@ -5584,9 +5582,6 @@ int nghttp2_session_pack_data(nghttp2_session *session,
     if(frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
       flags |= NGHTTP2_FLAG_END_STREAM;
     }
-    if(frame->hd.flags & NGHTTP2_FLAG_END_SEGMENT) {
-      flags |= NGHTTP2_FLAG_END_SEGMENT;
-    }
   }
 
   /* The primary reason of data_frame is pass to the user callback */
diff --git a/lib/nghttp2_submit.c b/lib/nghttp2_submit.c
index c9e65f2c..eea748b9 100644
--- a/lib/nghttp2_submit.c
+++ b/lib/nghttp2_submit.c
@@ -81,9 +81,7 @@ static int32_t submit_headers_shared
   }
 
   flags_copy =
-    (flags & (NGHTTP2_FLAG_END_STREAM |
-              NGHTTP2_FLAG_END_SEGMENT |
-              NGHTTP2_FLAG_PRIORITY)) |
+    (flags & (NGHTTP2_FLAG_END_STREAM | NGHTTP2_FLAG_PRIORITY)) |
     NGHTTP2_FLAG_END_HEADERS;
 
   if(stream_id == -1) {
@@ -538,8 +536,7 @@ int nghttp2_submit_data(nghttp2_session *session, uint8_t flags,
 {
   int rv;
   nghttp2_private_data *data_frame;
-  uint8_t nflags = flags & (NGHTTP2_FLAG_END_STREAM |
-                            NGHTTP2_FLAG_END_SEGMENT);
+  uint8_t nflags = flags & NGHTTP2_FLAG_END_STREAM;
 
   if(stream_id == 0) {
     return NGHTTP2_ERR_INVALID_ARGUMENT;
diff --git a/src/app_helper.cc b/src/app_helper.cc
index 756fa519..b82f8ec3 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -221,12 +221,6 @@ void print_flags(const nghttp2_frame_hd& hd)
     if(hd.flags & NGHTTP2_FLAG_END_STREAM) {
       s += "END_STREAM";
     }
-    if(hd.flags & NGHTTP2_FLAG_END_SEGMENT) {
-      if(!s.empty()) {
-        s += " | ";
-      }
-      s += "END_SEGMENT";
-    }
     if(hd.flags & NGHTTP2_FLAG_PADDED) {
       if(!s.empty()) {
         s += " | ";
@@ -238,12 +232,6 @@ void print_flags(const nghttp2_frame_hd& hd)
     if(hd.flags & NGHTTP2_FLAG_END_STREAM) {
       s += "END_STREAM";
     }
-    if(hd.flags & NGHTTP2_FLAG_END_SEGMENT) {
-      if(!s.empty()) {
-        s += " | ";
-      }
-      s += "END_SEGMENT";
-    }
     if(hd.flags & NGHTTP2_FLAG_END_HEADERS) {
       if(!s.empty()) {
         s += " | ";
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index bf89121b..567cd2ee 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -2989,8 +2989,7 @@ void test_nghttp2_submit_data(void)
                               &pri_spec_default, NGHTTP2_STREAM_OPENING,
                               NULL);
   CU_ASSERT(0 == nghttp2_submit_data(session,
-                                     NGHTTP2_FLAG_END_STREAM |
-                                     NGHTTP2_FLAG_END_SEGMENT, 1, &data_prd));
+                                     NGHTTP2_FLAG_END_STREAM, 1, &data_prd));
 
   ud.block_count = 0;
   CU_ASSERT(0 == nghttp2_session_send(session));
@@ -3001,8 +3000,7 @@ void test_nghttp2_submit_data(void)
 
   CU_ASSERT(NGHTTP2_FLAG_NONE == hd.flags);
   /* frame->hd.flags has these flags */
-  CU_ASSERT((NGHTTP2_FLAG_END_STREAM | NGHTTP2_FLAG_END_SEGMENT) ==
-            data_frame->hd.flags);
+  CU_ASSERT(NGHTTP2_FLAG_END_STREAM == data_frame->hd.flags);
 
   nghttp2_session_del(session);
 }