diff --git a/subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbuffer.c b/subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbuffer.c
index ce3949a6b8..399724d8dd 100644
--- a/subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbuffer.c
+++ b/subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbuffer.c
@@ -833,6 +833,8 @@ ensure_buffers (GstRTPBuffer * rtp)
  * extension header. If the existing extension data is not large enough, it will
  * be made larger.
  *
+ * Will also shorten the extension data from 1.20.
+ *
  * Returns: True if done.
  */
 gboolean
@@ -882,6 +884,15 @@ gst_rtp_buffer_set_extension_data (GstRTPBuffer * rtp, guint16 bits,
     gst_memory_ref (mem);
     rtp->data[1] = rtp->map[1].data;
     rtp->size[1] = rtp->map[1].size;
+  } else if (min_size < rtp->size[1]) {
+    GstMemory *mem = rtp->map[1].memory;
+
+    gst_memory_ref (mem);
+    gst_buffer_unmap (rtp->buffer, &rtp->map[1]);
+    gst_memory_resize (mem, 0, min_size);
+    gst_memory_map (mem, &rtp->map[1], GST_MAP_READWRITE);
+    rtp->data[1] = rtp->map[1].data;
+    rtp->size[1] = rtp->map[1].size;
   }
 
   /* now we can set the extension bit */
diff --git a/subprojects/gst-plugins-base/tests/check/libs/rtp.c b/subprojects/gst-plugins-base/tests/check/libs/rtp.c
index 029260d47d..11eec6d0c4 100644
--- a/subprojects/gst-plugins-base/tests/check/libs/rtp.c
+++ b/subprojects/gst-plugins-base/tests/check/libs/rtp.c
@@ -421,6 +421,87 @@ GST_START_TEST (test_rtp_buffer_set_extension_data)
 
 GST_END_TEST;
 
+GST_START_TEST (test_rtp_buffer_set_extension_data_shrink_data)
+{
+  GstBuffer *buf;
+  guint16 bits;
+  guint size;
+  gpointer pointer;
+  GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
+  guint8 scratch_cmp[4 * 4] = { 0, };
+  GstMapInfo info = GST_MAP_INFO_INIT;
+  gsize i;
+
+  buf = gst_rtp_buffer_new_allocate (20, 0, 0);
+  gst_rtp_buffer_map (buf, GST_MAP_READWRITE, &rtp);
+
+  fail_unless (gst_rtp_buffer_set_extension_data (&rtp, 270, 4) == TRUE);
+  fail_unless (gst_rtp_buffer_get_extension (&rtp) == TRUE);
+  gst_rtp_buffer_get_extension_data (&rtp, &bits, &pointer, &size);
+  GST_MEMDUMP ("", pointer, size * 4);
+  fail_unless (bits == 270);
+  fail_unless (size == 4);
+  for (i = 0; i < size * 4; i++) {
+    guint8 *bytes = pointer;
+    bytes[i] = i;
+  }
+  memcpy (scratch_cmp, pointer, size * 4);
+  fail_unless_equals_int64 ((guint64) gst_buffer_get_size (buf), 52);
+  gst_rtp_buffer_unmap (&rtp);
+
+  /* ensure that the mapped buffer size matches */
+  gst_buffer_map (buf, &info, GST_MAP_READ);
+  GST_MEMDUMP ("", info.data, info.size);
+  fail_unless_equals_int64 ((guint64) info.size, 52);
+  gst_buffer_unmap (buf, &info);
+
+  gst_rtp_buffer_map (buf, GST_MAP_READWRITE, &rtp);
+  /* shrinking the extension data should still succeed and only output the
+   * relevant data */
+  fail_unless (gst_rtp_buffer_set_extension_data (&rtp, 180, 2) == TRUE);
+  gst_rtp_buffer_get_extension_data (&rtp, &bits, &pointer, &size);
+  GST_MEMDUMP ("", pointer, size * 4);
+  fail_unless (bits == 180);
+  fail_unless (size == 2);
+  fail_unless_equals_int64 ((guint64) gst_buffer_get_size (buf), 44);
+  for (i = 0; i < 8; i++) {
+    guint8 *ext_data = pointer;
+    fail_unless_equals_int_hex (ext_data[i], scratch_cmp[i]);
+  }
+  gst_rtp_buffer_unmap (&rtp);
+
+  gst_buffer_map (buf, &info, GST_MAP_READ);
+  GST_MEMDUMP ("", info.data, info.size);
+  fail_unless_equals_int64 ((guint64) info.size, 44);
+  gst_buffer_unmap (buf, &info);
+
+  gst_rtp_buffer_map (buf, GST_MAP_READWRITE, &rtp);
+  fail_unless (gst_rtp_buffer_set_extension_data (&rtp, 308, 3) == TRUE);
+  gst_rtp_buffer_get_extension_data (&rtp, &bits, &pointer, &size);
+  GST_MEMDUMP ("", pointer, size * 4);
+  fail_unless (bits == 308);
+  fail_unless (size == 3);
+  for (i = 0; i < 8; i++) {
+    guint8 *ext_data = pointer;
+    fail_unless_equals_int_hex (ext_data[i], scratch_cmp[i]);
+  }
+  /* new data will be zero-initialized */
+  for (i = 8; i < size * 4; i++) {
+    guint8 *ext_data = pointer;
+    fail_unless_equals_int_hex (ext_data[i], 0);
+  }
+  fail_unless_equals_int64 ((guint64) gst_buffer_get_size (buf), 48);
+  gst_rtp_buffer_unmap (&rtp);
+
+  gst_buffer_map (buf, &info, GST_MAP_READ);
+  GST_MEMDUMP ("", info.data, info.size);
+  fail_unless_equals_int64 ((guint64) info.size, 48);
+  gst_buffer_unmap (buf, &info);
+  gst_buffer_unref (buf);
+}
+
+GST_END_TEST;
+
 #if 0
 GST_START_TEST (test_rtp_buffer_list_set_extension)
 {
@@ -2290,6 +2371,7 @@ rtp_suite (void)
   tcase_add_test (tc_chain, test_rtcp_compound_padding);
   tcase_add_test (tc_chain, test_rtp_buffer_extlen_wraparound);
   tcase_add_test (tc_chain, test_rtp_buffer_remove_extension_data);
+  tcase_add_test (tc_chain, test_rtp_buffer_set_extension_data_shrink_data);
 
   return s;
 }