diff --git a/grc/gsm_block_tree.xml b/grc/gsm_block_tree.xml
index c275c2d..9951e71 100644
--- a/grc/gsm_block_tree.xml
+++ b/grc/gsm_block_tree.xml
@@ -42,6 +42,7 @@
       <block>gsm_burst_timeslot_splitter</block>
       <block>gsm_burst_sdcch_subslot_splitter</block>
       <block>gsm_burst_timeslot_filter</block>
+      <block>gsm_burst_sdcch_subslot_filter</block>
       <block>gsm_burst_fnr_filter</block>
       <block>gsm_dummy_burst_filter</block>
     </cat>