1 files changed, 5 insertions, 4 deletions
diff --git a/src/support/insert_ordered.h b/src/support/insert_ordered.h
index 1460c4329..f39eb61b0 100644
--- a/src/support/insert_ordered.h
+++ b/src/support/insert_ordered.h
@@ -50,12 +50,13 @@ template<typename T> struct InsertOrderedSet {
   }
 
   // cheating a bit, not returning the iterator
-  void insert(const T& val) {
-    auto it = Map.find(val);
-    if (it == Map.end()) {
+  bool insert(const T& val) {
+    auto [it, inserted] = Map.insert({val, List.begin()});
+    if (inserted) {
       List.push_back(val);
-      Map.insert(std::make_pair(val, --List.end()));
+      it->second = --List.end();
     }
+    return inserted;
   }
 
   size_t size() const { return Map.size(); }