diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index 45e53589..0aab61d8 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -766,10 +766,17 @@ ssize_t nghttp2_hd_deflate_hd(nghttp2_hd_context *deflater,
         /* Check name exists in hd_table */
         ent = find_name_in_hd_table(deflater, &nv[i]);
         if(ent) {
-          /* As long as no eviction kicked in, perform substitution */
-          if(require_eviction_on_subst(deflater, &nv[i], ent)) {
+          /* As long as no eviction kicked in and the same header
+             field name is not indexed and added, perform
+             substitution. Since we never evict anything, searching
+             ent->index in working set is safe. */
+          if(require_eviction_on_subst(deflater, &nv[i], ent) ||
+             find_in_workingset_by_index(deflater, ent->index)) {
             rv = emit_indname_block(buf_ptr, buflen_ptr, &offset, ent,
                                     nv[i].value, nv[i].valuelen, 0);
+            if(rv < 0) {
+              return rv;
+            }
           } else {
             nghttp2_hd_entry *new_ent;
             /* No need to increment ent->ref here */
diff --git a/tests/nghttp2_hd_test.c b/tests/nghttp2_hd_test.c
index d66867db..cc5eb6b6 100644
--- a/tests/nghttp2_hd_test.c
+++ b/tests/nghttp2_hd_test.c
@@ -51,6 +51,12 @@ void test_nghttp2_hd_deflate(void)
                        MAKE_NV("hello", "world")};
   nghttp2_nv nva2[] = {MAKE_NV(":path", "/script.js"),
                        MAKE_NV(":scheme", "https")};
+  nghttp2_nv nva3[] = {MAKE_NV(":path", "/style.css"),
+                       MAKE_NV("cookie", "k1=v1"),
+                       MAKE_NV("cookie", "k2=v2")};
+  nghttp2_nv nva4[] = {MAKE_NV(":path", "/style.css"),
+                       MAKE_NV("cookie", "k1=v1"),
+                       MAKE_NV("cookie", "k1=v1")};
   size_t nv_offset = 12;
   uint8_t *buf = NULL;
   size_t buflen = 0;
@@ -89,6 +95,36 @@ void test_nghttp2_hd_deflate(void)
   nghttp2_nv_array_del(resnva);
   nghttp2_hd_end_headers(&inflater);
 
+  /* Third headers, including same header field name, but value is not
+     the same. */
+  blocklen = nghttp2_hd_deflate_hd(&deflater, &buf, &buflen, nv_offset, nva3,
+                                   sizeof(nva3)/sizeof(nghttp2_nv));
+  CU_ASSERT(blocklen > 0);
+  nghttp2_hd_end_headers(&deflater);
+
+  CU_ASSERT(3 == nghttp2_hd_inflate_hd(&inflater, &resnva, buf + nv_offset,
+                                       blocklen));
+
+  assert_nv_equal(nva3, resnva, 3);
+
+  nghttp2_nv_array_del(resnva);
+  nghttp2_hd_end_headers(&inflater);
+
+  /* Fourth headers, including duplicate header fields. We don't
+     encode duplicates. Only first one is encoded. */
+  blocklen = nghttp2_hd_deflate_hd(&deflater, &buf, &buflen, nv_offset, nva4,
+                                   sizeof(nva4)/sizeof(nghttp2_nv));
+  CU_ASSERT(blocklen == 0);
+  nghttp2_hd_end_headers(&deflater);
+
+  CU_ASSERT(2 == nghttp2_hd_inflate_hd(&inflater, &resnva, buf + nv_offset,
+                                       blocklen));
+
+  assert_nv_equal(nva4, resnva, 2);
+
+  nghttp2_nv_array_del(resnva);
+  nghttp2_hd_end_headers(&inflater);
+
   free(buf);
   nghttp2_hd_inflate_free(&inflater);
   nghttp2_hd_deflate_free(&deflater);