diff --git a/src/newgrf_badge.cpp b/src/newgrf_badge.cpp
index 9a01139be1..ee0b39742c 100644
--- a/src/newgrf_badge.cpp
+++ b/src/newgrf_badge.cpp
@@ -318,10 +318,7 @@ BadgeTextFilter::BadgeTextFilter(StringFilter &filter, GrfSpecFeature feature)
 		filter.AddLine(GetString(badge.name));
 		if (!filter.GetState()) continue;
 
-		auto it = std::ranges::lower_bound(this->badges, badge.index);
-		if (it != std::end(this->badges) && *it == badge.index) continue;
-
-		this->badges.insert(it, badge.index);
+		this->badges.insert(badge.index);
 	}
 }
 
diff --git a/src/newgrf_badge.h b/src/newgrf_badge.h
index dca2bd6995..684bf08a5b 100644
--- a/src/newgrf_badge.h
+++ b/src/newgrf_badge.h
@@ -10,6 +10,7 @@
 #ifndef NEWGRF_BADGE_H
 #define NEWGRF_BADGE_H
 
+#include "core/flatset_type.hpp"
 #include "newgrf.h"
 #include "newgrf_badge_type.h"
 #include "newgrf_commons.h"
@@ -65,7 +66,7 @@ public:
 	bool Filter(std::span<const BadgeID> badges) const;
 
 private:
-	std::vector<BadgeID> badges{};
+	FlatSet<BadgeID> badges{};
 };
 
 #endif /* NEWGRF_BADGE_H */
diff --git a/src/newgrf_badge_gui.cpp b/src/newgrf_badge_gui.cpp
index a65b06ff11..59bcbdb427 100644
--- a/src/newgrf_badge_gui.cpp
+++ b/src/newgrf_badge_gui.cpp
@@ -9,6 +9,7 @@
 
 #include "stdafx.h"
 
+#include "core/flatset_type.hpp"
 #include "dropdown_type.h"
 #include "newgrf.h"
 #include "newgrf_badge.h"
@@ -120,7 +121,7 @@ int DrawBadgeNameList(Rect r, std::span<const BadgeID> badges, GrfSpecFeature)
 {
 	if (badges.empty()) return r.top;
 
-	std::set<BadgeClassID> class_indexes;
+	FlatSet<BadgeClassID> class_indexes;
 	for (const BadgeID &index : badges) class_indexes.insert(GetBadge(index)->class_index);
 
 	std::string_view list_separator = GetListSeparator();