diff --git a/grc/gsm_block_tree.xml b/grc/gsm_block_tree.xml
index 1b8cd03..a76547a 100644
--- a/grc/gsm_block_tree.xml
+++ b/grc/gsm_block_tree.xml
@@ -40,6 +40,7 @@
     <cat>
       <name>Flow control</name>
       <block>gsm_burst_timeslot_splitter</block>
+      <block>gsm_burst_sdcch_subslot_splitter</block>
       <block>gsm_burst_fnr_filter</block>
       <block>gsm_dummy_burst_filter</block>
     </cat>