diff --git a/src/api/sorting/plugin_sort.cpp b/src/api/sorting/plugin_sort.cpp
index 4a9bacd5..a384712f 100644
--- a/src/api/sorting/plugin_sort.cpp
+++ b/src/api/sorting/plugin_sort.cpp
@@ -309,8 +309,8 @@ std::vector<std::string> SortPlugins(
 
 std::vector<std::string> SortPlugins(
     std::vector<PluginSortingData>&& pluginsSortingData,
-    const std::vector<Group> masterlistGroups,
-    const std::vector<Group> userGroups,
+    const std::vector<Group>& masterlistGroups,
+    const std::vector<Group>& userGroups,
     const std::vector<std::string>& earlyLoadingPlugins) {
   // If there aren't any plugins, exit early, because sorting assumes
   // there is at least one plugin.
diff --git a/src/api/sorting/plugin_sort.h b/src/api/sorting/plugin_sort.h
index 1d87562c..eb8cf44e 100644
--- a/src/api/sorting/plugin_sort.h
+++ b/src/api/sorting/plugin_sort.h
@@ -34,8 +34,8 @@
 namespace loot {
 std::vector<std::string> SortPlugins(
     std::vector<PluginSortingData>&& pluginsSortingData,
-    const std::vector<Group> masterlistGroups,
-    const std::vector<Group> userGroups,
+    const std::vector<Group>& masterlistGroups,
+    const std::vector<Group>& userGroups,
     const std::vector<std::string>& earlyLoadingPlugins);
 
 std::vector<std::string> SortPlugins(Game& game,