diff --git a/ucode/sort4.uc b/ucode/sort4.uc
index 7c36937..b14cef7 100644
--- a/ucode/sort4.uc
+++ b/ucode/sort4.uc
@@ -121,6 +121,7 @@ $MERGE
 // Load bucket size
 mov ar asr
 mov pm lc
+bls @MERGE_BOTTOM
 
 // Copy elements to list
 $MERGE_MOVE