diff --git a/lib/config/applyrule-targeted.cpp b/lib/config/applyrule-targeted.cpp
index 8a4b2fd45..210c67764 100644
--- a/lib/config/applyrule-targeted.cpp
+++ b/lib/config/applyrule-targeted.cpp
@@ -11,7 +11,7 @@ using namespace icinga;
 /**
  * @returns All ApplyRules targeting only specific parent objects including the given host. (See AddTargetedRule().)
  */
-const std::vector<ApplyRule::Ptr>& ApplyRule::GetTargetedHostRules(const Type::Ptr& sourceType, const String& host)
+const std::set<ApplyRule::Ptr>& ApplyRule::GetTargetedHostRules(const Type::Ptr& sourceType, const String& host)
 {
 	auto perSourceType (m_Rules.find(sourceType.get()));
 
@@ -23,14 +23,14 @@ const std::vector<ApplyRule::Ptr>& ApplyRule::GetTargetedHostRules(const Type::P
 		}
 	}
 
-	static const std::vector<ApplyRule::Ptr> noRules;
+	static const std::set<ApplyRule::Ptr> noRules;
 	return noRules;
 }
 
 /**
  * @returns All ApplyRules targeting only specific parent objects including the given service. (See AddTargetedRule().)
  */
-const std::vector<ApplyRule::Ptr>& ApplyRule::GetTargetedServiceRules(const Type::Ptr& sourceType, const String& host, const String& service)
+const std::set<ApplyRule::Ptr>& ApplyRule::GetTargetedServiceRules(const Type::Ptr& sourceType, const String& host, const String& service)
 {
 	auto perSourceType (m_Rules.find(sourceType.get()));
 
@@ -46,7 +46,7 @@ const std::vector<ApplyRule::Ptr>& ApplyRule::GetTargetedServiceRules(const Type
 		}
 	}
 
-	static const std::vector<ApplyRule::Ptr> noRules;
+	static const std::set<ApplyRule::Ptr> noRules;
 	return noRules;
 }
 
@@ -67,7 +67,7 @@ bool ApplyRule::AddTargetedRule(const ApplyRule::Ptr& rule, const String& target
 
 		if (GetTargetHosts(rule->m_Filter.get(), hosts)) {
 			for (auto host : hosts) {
-				rules.Targeted[*host].ForHost.emplace_back(rule);
+				rules.Targeted[*host].ForHost.emplace(rule);
 			}
 
 			return true;
@@ -77,7 +77,7 @@ bool ApplyRule::AddTargetedRule(const ApplyRule::Ptr& rule, const String& target
 
 		if (GetTargetServices(rule->m_Filter.get(), services)) {
 			for (auto service : services) {
-				rules.Targeted[*service.first].ForServices[*service.second].emplace_back(rule);
+				rules.Targeted[*service.first].ForServices[*service.second].emplace(rule);
 			}
 
 			return true;
diff --git a/lib/config/applyrule.hpp b/lib/config/applyrule.hpp
index 3756ede52..6b6fca8f8 100644
--- a/lib/config/applyrule.hpp
+++ b/lib/config/applyrule.hpp
@@ -23,8 +23,8 @@ public:
 
 	struct PerHost
 	{
-		std::vector<ApplyRule::Ptr> ForHost;
-		std::unordered_map<String /* service */, std::vector<ApplyRule::Ptr>> ForServices;
+		std::set<ApplyRule::Ptr> ForHost;
+		std::unordered_map<String /* service */, std::set<ApplyRule::Ptr>> ForServices;
 	};
 
 	struct PerSourceType
@@ -36,13 +36,13 @@ public:
 	/*
 	 * m_Rules[T::TypeInstance.get()].Targeted["H"].ForHost
 	 * contains all apply rules like apply T "x" to Host { ... }
-	 * which target only specific hosts incl. "H", e. g. via
+	 * which target only specific hosts incl. "H", e.g. via
 	 * assign where host.name == "H" || host.name == "h".
 	 *
 	 * m_Rules[T::TypeInstance.get()].Targeted["H"].ForServices["S"]
 	 * contains all apply rules like apply T "x" to Service { ... }
-	 * which target only specific services on specific hosts incl. "H!S",
-	 * e. g. via assign where host.name == "H" && service.name == "S".
+	 * which target only specific services on specific hosts,
+	 * e.g. via assign where host.name == "H" && service.name == "S".
 	 *
 	 * m_Rules[T::TypeInstance.get()].Regular[C::TypeInstance.get()]
 	 * contains all other apply rules like apply T "x" to C { ... }.
@@ -70,8 +70,8 @@ public:
 		const Expression::Ptr& filter, const String& package, const String& fkvar, const String& fvvar, const Expression::Ptr& fterm,
 		bool ignoreOnError, const DebugInfo& di, const Dictionary::Ptr& scope);
 	static const std::vector<ApplyRule::Ptr>& GetRules(const Type::Ptr& sourceType, const Type::Ptr& targetType);
-	static const std::vector<ApplyRule::Ptr>& GetTargetedHostRules(const Type::Ptr& sourceType, const String& host);
-	static const std::vector<ApplyRule::Ptr>& GetTargetedServiceRules(const Type::Ptr& sourceType, const String& host, const String& service);
+	static const std::set<ApplyRule::Ptr>& GetTargetedHostRules(const Type::Ptr& sourceType, const String& host);
+	static const std::set<ApplyRule::Ptr>& GetTargetedServiceRules(const Type::Ptr& sourceType, const String& host, const String& service);
 
 	static void RegisterType(const String& sourceType, const std::vector<String>& targetTypes);
 	static bool IsValidSourceType(const String& sourceType);