diff --git a/src/log_surgeon/finite_automata/RegexAST.hpp b/src/log_surgeon/finite_automata/RegexAST.hpp
index b3671337..70d76d98 100644
--- a/src/log_surgeon/finite_automata/RegexAST.hpp
+++ b/src/log_surgeon/finite_automata/RegexAST.hpp
@@ -89,8 +89,8 @@ class RegexAST {
         m_subtree_positive_tags.insert(subtree_positive_tags.begin(), subtree_positive_tags.end());
     }
 
-    auto set_negative_tags(std::set<uint32_t> const& negative_tags) -> void {
-        m_negative_tags = negative_tags;
+    auto set_negative_tags(std::set<uint32_t> negative_tags) -> void {
+        m_negative_tags = std::move(negative_tags);
     }
 
 protected: