diff --git a/grc/gsm_block_tree.xml b/grc/gsm_block_tree.xml
index 5837ce2..2864e4d 100644
--- a/grc/gsm_block_tree.xml
+++ b/grc/gsm_block_tree.xml
@@ -52,6 +52,7 @@
       <block>gsm_clock_offset_corrector</block>
       <block>gsm_tmsi_dumper</block>
       <block>gsm_message_source</block>
+      <block>gsm_message_sink</block>
     </cat>
   </cat>
 </cat>