diff --git a/lib/nghttp2_frame.c b/lib/nghttp2_frame.c
index b4c1d443..4f42605a 100644
--- a/lib/nghttp2_frame.c
+++ b/lib/nghttp2_frame.c
@@ -741,6 +741,30 @@ void nghttp2_frame_unpack_altsvc_payload(nghttp2_extension *frame,
   altsvc->field_value_len = (size_t)(payload + payloadlen - p);
 }
 
+int nghttp2_frame_unpack_altsvc_payload2(nghttp2_extension *frame,
+                                         const uint8_t *payload,
+                                         size_t payloadlen, nghttp2_mem *mem) {
+  uint8_t *buf;
+  size_t origin_len;
+
+  if (payloadlen < 2) {
+    return NGHTTP2_FRAME_SIZE_ERROR;
+  }
+
+  origin_len = nghttp2_get_uint16(payload);
+
+  buf = nghttp2_mem_malloc(mem, payloadlen - 2);
+  if (!buf) {
+    return NGHTTP2_ERR_NOMEM;
+  }
+
+  nghttp2_cpymem(buf, payload + 2, payloadlen - 2);
+
+  nghttp2_frame_unpack_altsvc_payload(frame, origin_len, buf, payloadlen - 2);
+
+  return 0;
+}
+
 nghttp2_settings_entry *nghttp2_frame_iv_copy(const nghttp2_settings_entry *iv,
                                               size_t niv, nghttp2_mem *mem) {
   nghttp2_settings_entry *iv_copy;
diff --git a/lib/nghttp2_frame.h b/lib/nghttp2_frame.h
index c6111728..c6ebcb06 100644
--- a/lib/nghttp2_frame.h
+++ b/lib/nghttp2_frame.h
@@ -388,6 +388,24 @@ int nghttp2_frame_pack_altsvc(nghttp2_bufs *bufs, nghttp2_extension *ext);
 void nghttp2_frame_unpack_altsvc_payload(nghttp2_extension *frame,
                                          size_t origin_len, uint8_t *payload,
                                          size_t payloadlen);
+
+/*
+ * Unpacks ALTSVC wire format into |frame|.  This function only exists
+ * for unit test.  After allocating buffer for fields, this function
+ * internally calls nghttp2_frame_unpack_altsvc_payload().
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * NGHTTP2_ERR_NOMEM
+ *     Out of memory.
+ * NGHTTP2_ERR_FRAME_SIZE_ERROR
+ *     The payload is too small.
+ */
+int nghttp2_frame_unpack_altsvc_payload2(nghttp2_extension *frame,
+                                         const uint8_t *payload,
+                                         size_t payloadlen, nghttp2_mem *mem);
+
 /*
  * Initializes HEADERS frame |frame| with given values.  |frame| takes
  * ownership of |nva|, so caller must not free it. If |stream_id| is
diff --git a/tests/main.c b/tests/main.c
index 3aae0376..0b17dcd7 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -339,6 +339,8 @@ int main(int argc _U_, char *argv[] _U_) {
                    test_nghttp2_frame_pack_goaway) ||
       !CU_add_test(pSuite, "frame_pack_window_update",
                    test_nghttp2_frame_pack_window_update) ||
+      !CU_add_test(pSuite, "frame_pack_altsvc",
+                   test_nghttp2_frame_pack_altsvc) ||
       !CU_add_test(pSuite, "nv_array_copy", test_nghttp2_nv_array_copy) ||
       !CU_add_test(pSuite, "iv_check", test_nghttp2_iv_check) ||
       !CU_add_test(pSuite, "hd_deflate", test_nghttp2_hd_deflate) ||
diff --git a/tests/nghttp2_frame_test.c b/tests/nghttp2_frame_test.c
index 06d83448..17b7ae58 100644
--- a/tests/nghttp2_frame_test.c
+++ b/tests/nghttp2_frame_test.c
@@ -454,6 +454,60 @@ void test_nghttp2_frame_pack_window_update(void) {
   nghttp2_frame_window_update_free(&frame);
 }
 
+void test_nghttp2_frame_pack_altsvc(void) {
+  nghttp2_extension frame, oframe;
+  nghttp2_ext_altsvc altsvc, oaltsvc;
+  nghttp2_bufs bufs;
+  int rv;
+  size_t payloadlen;
+  static const uint8_t origin[] = "nghttp2.org";
+  static const uint8_t field_value[] = "h2=\":443\"";
+  nghttp2_buf buf;
+  uint8_t *rawbuf;
+  nghttp2_mem *mem;
+
+  mem = nghttp2_mem_default();
+
+  frame_pack_bufs_init(&bufs);
+
+  frame.payload = &altsvc;
+  oframe.payload = &oaltsvc;
+
+  rawbuf = nghttp2_mem_malloc(mem, 32);
+  nghttp2_buf_wrap_init(&buf, rawbuf, 32);
+
+  buf.last = nghttp2_cpymem(buf.last, origin, sizeof(origin) - 1);
+  buf.last = nghttp2_cpymem(buf.last, field_value, sizeof(field_value) - 1);
+
+  nghttp2_frame_altsvc_init(&frame, 1000000007, buf.pos, sizeof(origin) - 1,
+                            buf.pos + sizeof(origin) - 1,
+                            sizeof(field_value) - 1);
+
+  payloadlen = 2 + sizeof(origin) - 1 + sizeof(field_value) - 1;
+
+  rv = nghttp2_frame_pack_altsvc(&bufs, &frame);
+
+  CU_ASSERT(0 == rv);
+  CU_ASSERT(NGHTTP2_FRAME_HDLEN + payloadlen == nghttp2_bufs_len(&bufs));
+
+  rv = unpack_framebuf((nghttp2_frame*)&oframe, &bufs);
+
+  CU_ASSERT(0 == rv);
+
+  check_frame_header(payloadlen, NGHTTP2_ALTSVC, NGHTTP2_FLAG_NONE, 1000000007,
+                     &oframe.hd);
+
+  CU_ASSERT(sizeof(origin) - 1 == oaltsvc.origin_len);
+  CU_ASSERT(0 == memcmp(origin, oaltsvc.origin, sizeof(origin) - 1));
+  CU_ASSERT(sizeof(field_value) - 1 == oaltsvc.field_value_len);
+  CU_ASSERT(0 ==
+            memcmp(field_value, oaltsvc.field_value, sizeof(field_value) - 1));
+
+  nghttp2_frame_altsvc_free(&oframe, mem);
+  nghttp2_frame_altsvc_free(&frame, mem);
+  nghttp2_bufs_free(&bufs);
+}
+
 void test_nghttp2_nv_array_copy(void) {
   nghttp2_nv *nva;
   ssize_t rv;
diff --git a/tests/nghttp2_frame_test.h b/tests/nghttp2_frame_test.h
index f3f4530e..059b20ba 100644
--- a/tests/nghttp2_frame_test.h
+++ b/tests/nghttp2_frame_test.h
@@ -38,6 +38,7 @@ void test_nghttp2_frame_pack_push_promise(void);
 void test_nghttp2_frame_pack_ping(void);
 void test_nghttp2_frame_pack_goaway(void);
 void test_nghttp2_frame_pack_window_update(void);
+void test_nghttp2_frame_pack_altsvc(void);
 void test_nghttp2_nv_array_copy(void);
 void test_nghttp2_iv_check(void);
 
diff --git a/tests/nghttp2_test_helper.c b/tests/nghttp2_test_helper.c
index ed92f132..dcd4ddb8 100644
--- a/tests/nghttp2_test_helper.c
+++ b/tests/nghttp2_test_helper.c
@@ -83,6 +83,10 @@ int unpack_frame(nghttp2_frame *frame, const uint8_t *in, size_t len) {
     nghttp2_frame_unpack_window_update_payload(&frame->window_update, payload,
                                                payloadlen);
     break;
+  case NGHTTP2_ALTSVC:
+    assert(payloadlen > 2);
+    nghttp2_frame_unpack_altsvc_payload2(&frame->ext, payload, payloadlen, mem);
+    break;
   default:
     /* Must not be reachable */
     assert(0);