diff --git a/test/external_frame_buffer_test.cc b/test/external_frame_buffer_test.cc
index 874d1997c..e50340159 100644
--- a/test/external_frame_buffer_test.cc
+++ b/test/external_frame_buffer_test.cc
@@ -252,42 +252,51 @@ TEST_P(ExternalFrameBufferMD5Test, ExtFBMD5Match) {
   delete video;
 }
 
-TEST_F(ExternalFrameBufferTest, EightFrameBuffers) {
-  // Minimum number of reference buffers for VP9 is 8.
-  const int num_buffers = 8;
+TEST_F(ExternalFrameBufferTest, NineFrameBuffers) {
+  // Minimum number of external frame buffers for VP9 is
+  // #VP9_MAXIMUM_REF_BUFFERS + #VPX_MAXIMUM_WORK_BUFFERS.
+  const int num_buffers = VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS;
   ASSERT_EQ(VPX_CODEC_OK,
             SetExternalFrameBuffers(num_buffers, realloc_vp9_frame_buffer));
   ASSERT_EQ(VPX_CODEC_OK, DecodeRemainingFrames());
 }
 
 TEST_F(ExternalFrameBufferTest, EightJitterBuffers) {
-  // Number of buffers equals number of possible reference buffers(8), plus
-  // one working buffer, plus eight jitter buffers.
-  const int num_buffers = 17;
+  // Number of buffers equals #VP9_MAXIMUM_REF_BUFFERS +
+  // #VPX_MAXIMUM_WORK_BUFFERS + eight jitter buffers.
+  const int jitter_buffers = 8;
+  const int num_buffers =
+      VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS + jitter_buffers;
   ASSERT_EQ(VPX_CODEC_OK,
             SetExternalFrameBuffers(num_buffers, realloc_vp9_frame_buffer));
   ASSERT_EQ(VPX_CODEC_OK, DecodeRemainingFrames());
 }
 
 TEST_F(ExternalFrameBufferTest, NotEnoughBuffers) {
-  // Minimum number of reference buffers for VP9 is 8.
-  const int num_buffers = 7;
+  // Minimum number of external frame buffers for VP9 is
+  // #VP9_MAXIMUM_REF_BUFFERS + #VPX_MAXIMUM_WORK_BUFFERS. Set one less.
+  const int num_buffers =
+      VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS - 1;
   ASSERT_EQ(VPX_CODEC_INVALID_PARAM,
             SetExternalFrameBuffers(num_buffers, realloc_vp9_frame_buffer));
 }
 
 TEST_F(ExternalFrameBufferTest, NullFrameBufferList) {
-  // Number of buffers equals number of possible reference buffers(8), plus
-  // one working buffer, plus four jitter buffers.
-  const int num_buffers = 13;
+  // Number of buffers equals #VP9_MAXIMUM_REF_BUFFERS +
+  // #VPX_MAXIMUM_WORK_BUFFERS + four jitter buffers.
+  const int jitter_buffers = 4;
+  const int num_buffers =
+      VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS + jitter_buffers;
   ASSERT_EQ(VPX_CODEC_INVALID_PARAM,
             SetNullFrameBuffers(num_buffers, realloc_vp9_frame_buffer));
 }
 
 TEST_F(ExternalFrameBufferTest, NullRealloc) {
-  // Number of buffers equals number of possible reference buffers(8), plus
-  // one working buffer, plus four jitter buffers.
-  const int num_buffers = 13;
+  // Number of buffers equals #VP9_MAXIMUM_REF_BUFFERS +
+  // #VPX_MAXIMUM_WORK_BUFFERS + four jitter buffers.
+  const int jitter_buffers = 4;
+  const int num_buffers =
+      VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS + jitter_buffers;
   ASSERT_EQ(VPX_CODEC_OK,
             SetExternalFrameBuffers(num_buffers,
                                     zero_realloc_vp9_frame_buffer));
@@ -295,9 +304,11 @@ TEST_F(ExternalFrameBufferTest, NullRealloc) {
 }
 
 TEST_F(ExternalFrameBufferTest, ReallocOneLessByte) {
-  // Number of buffers equals number of possible reference buffers(8), plus
-  // one working buffer, plus four jitter buffers.
-  const int num_buffers = 13;
+  // Number of buffers equals #VP9_MAXIMUM_REF_BUFFERS +
+  // #VPX_MAXIMUM_WORK_BUFFERS + four jitter buffers.
+  const int jitter_buffers = 4;
+  const int num_buffers =
+      VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS + jitter_buffers;
   ASSERT_EQ(VPX_CODEC_OK,
             SetExternalFrameBuffers(num_buffers,
                                     one_less_byte_realloc_vp9_frame_buffer));
diff --git a/vp9/vp9_dx_iface.c b/vp9/vp9_dx_iface.c
index c123c4653..445198bb4 100644
--- a/vp9/vp9_dx_iface.c
+++ b/vp9/vp9_dx_iface.c
@@ -508,8 +508,9 @@ static vpx_codec_err_t vp9_set_frame_buffers(
     vpx_codec_alg_priv_t *ctx,
     vpx_codec_frame_buffer_t *fb_list, int fb_count,
     vpx_realloc_frame_buffer_cb_fn_t cb, void *user_priv) {
-  if (fb_count < REF_FRAMES) {
-    /* The application must pass in at least REF_FRAMES frame buffers. */
+  if (fb_count < (VP9_MAXIMUM_REF_BUFFERS + VPX_MAXIMUM_WORK_BUFFERS)) {
+    /* The application must pass in at least VP9_MAXIMUM_REF_BUFFERS +
+     * VPX_MAXIMUM_WORK_BUFFERS frame buffers. */
     return VPX_CODEC_INVALID_PARAM;
   } else if (!ctx->pbi) {
     /* If the decoder has already been initialized, do not accept external
diff --git a/vpx/internal/vpx_codec_internal.h b/vpx/internal/vpx_codec_internal.h
index 6404b9872..6c644f045 100644
--- a/vpx/internal/vpx_codec_internal.h
+++ b/vpx/internal/vpx_codec_internal.h
@@ -239,8 +239,8 @@ typedef vpx_image_t *(*vpx_codec_get_frame_fn_t)(vpx_codec_alg_priv_t *ctx,
  *
  * \note
  * When decoding VP9, the application must pass in at least
- * #VP9_MAXIMUM_REF_BUFFERS external frame buffers, as VP9 can have up to
- * that many reference frames.
+ * #VP9_MAXIMUM_REF_BUFFERS + #VPX_MAXIMUM_WORK_BUFFERS external frame
+ * buffers.
  */
 typedef vpx_codec_err_t (*vpx_codec_set_frame_buffers_fn_t)(
     vpx_codec_alg_priv_t *ctx,
diff --git a/vpx/vpx_decoder.h b/vpx/vpx_decoder.h
index f28a07fb3..24be82d76 100644
--- a/vpx/vpx_decoder.h
+++ b/vpx/vpx_decoder.h
@@ -363,8 +363,8 @@ extern "C" {
    *
    * \note
    * When decoding VP9, the application must pass in at least
-   * #VP9_MAXIMUM_REF_BUFFERS external frame buffers, as VP9 can have up to
-   * that many reference frames.
+   * #VP9_MAXIMUM_REF_BUFFERS + #VPX_MAXIMUM_WORK_BUFFERS external frame
+   * buffers.
    */
   vpx_codec_err_t vpx_codec_set_frame_buffers(
       vpx_codec_ctx_t *ctx,