1 files changed, 5 insertions, 3 deletions
diff --git a/src/preprocessing/passes/bv_ackermann.h b/src/preprocessing/passes/bv_ackermann.h
index 197e92178..5f799ffe4 100644
--- a/src/preprocessing/passes/bv_ackermann.h
+++ b/src/preprocessing/passes/bv_ackermann.h
@@ -26,16 +26,18 @@
 #ifndef __CVC4__PREPROCESSING__PASSES__BV_ACKERMANN_H
 #define __CVC4__PREPROCESSING__PASSES__BV_ACKERMANN_H
 
+#include <unordered_map>
+#include "expr/node.h"
 #include "preprocessing/preprocessing_pass.h"
 #include "preprocessing/preprocessing_pass_context.h"
 
-#include <unordered_map>
-
 namespace CVC4 {
 namespace preprocessing {
 namespace passes {
 
-typedef std::unordered_map<Node, NodeSet, NodeHashFunction> FunctionToArgsMap;
+using TNodeSet = std::unordered_set<TNode, TNodeHashFunction>;
+using FunctionToArgsMap =
+    std::unordered_map<TNode, TNodeSet, TNodeHashFunction>;
 
 class BVAckermann : public PreprocessingPass
 {