diff --git a/passes/opt/opt_balance_tree.cc b/passes/opt/opt_balance_tree.cc
index f73b593df..0ab5aa838 100644
--- a/passes/opt/opt_balance_tree.cc
+++ b/passes/opt/opt_balance_tree.cc
@@ -330,7 +330,7 @@ struct OptBalanceTreePass : public Pass {
 
 		// Run splitfanout pass first
 		if (splitfanout)
-			Pass::call(design, "splitfanout t:$and t:$or t:$xor t:$add t:$mul");
+			Pass::call(design, "splitfanout t:$and t:$or t:$xor t:$xnor t:$add t:$mul");
 
 		// Count of all cells that were packed
 		dict<IdString, int> cell_count;