diff --git a/oscar64/InterCode.cpp b/oscar64/InterCode.cpp
index a60311f..ac4633b 100644
--- a/oscar64/InterCode.cpp
+++ b/oscar64/InterCode.cpp
@@ -22965,6 +22965,8 @@ void InterCodeProcedure::MergeBasicBlocks(FastNumberSet& activeSet)
 			ResetVisited();
 			mEntryBlock->FollowJumps();
 
+			BuildDataFlowSets();
+
 			changed = ShortLeaMerge(activeSet);
 		}