diff --git a/lib/base/function.hpp b/lib/base/function.hpp
index 780dae2c5..d52a230a1 100644
--- a/lib/base/function.hpp
+++ b/lib/base/function.hpp
@@ -60,28 +60,28 @@ private:
 	INITIALIZE_ONCE_WITH_PRIORITY([]() { \
 		Function::Ptr sf = new icinga::Function(#ns "#" #name, callback, String(args).Split(":"), false); \
 		Namespace::Ptr nsp = ScriptGlobal::Get(#ns); \
-		nsp->Set(#name, sf, true, true); \
+		nsp->Set(#name, sf, true); \
 	}, InitializePriority::RegisterFunctions)
 
 #define REGISTER_SAFE_FUNCTION(ns, name, callback, args) \
 	INITIALIZE_ONCE_WITH_PRIORITY([]() { \
 		Function::Ptr sf = new icinga::Function(#ns "#" #name, callback, String(args).Split(":"), true); \
 		Namespace::Ptr nsp = ScriptGlobal::Get(#ns); \
-		nsp->Set(#name, sf, true, true); \
+		nsp->Set(#name, sf, true); \
 	}, InitializePriority::RegisterFunctions)
 
 #define REGISTER_FUNCTION_NONCONST(ns, name, callback, args) \
 	INITIALIZE_ONCE_WITH_PRIORITY([]() { \
 		Function::Ptr sf = new icinga::Function(#ns "#" #name, callback, String(args).Split(":"), false); \
 		Namespace::Ptr nsp = ScriptGlobal::Get(#ns); \
-		nsp->Set(#name, sf, false, true); \
+		nsp->Set(#name, sf, false); \
 	}, InitializePriority::RegisterFunctions)
 
 #define REGISTER_SAFE_FUNCTION_NONCONST(ns, name, callback, args) \
 	INITIALIZE_ONCE_WITH_PRIORITY([]() { \
 		Function::Ptr sf = new icinga::Function(#ns "#" #name, callback, String(args).Split(":"), true); \
 		Namespace::Ptr nsp = ScriptGlobal::Get(#ns); \
-		nsp->SetAttribute(#name, sf, false, true); \
+		nsp->SetAttribute(#name, sf, false); \
 	}, InitializePriority::RegisterFunctions)
 
 }
diff --git a/lib/base/json-script.cpp b/lib/base/json-script.cpp
index 5738a33fa..90595c88f 100644
--- a/lib/base/json-script.cpp
+++ b/lib/base/json-script.cpp
@@ -24,5 +24,5 @@ INITIALIZE_ONCE([]() {
 	jsonNS->Freeze();
 
 	Namespace::Ptr systemNS = ScriptGlobal::Get("System");
-	systemNS->Set("Json", jsonNS, true, true);
+	systemNS->Set("Json", jsonNS, true);
 });
diff --git a/lib/base/math-script.cpp b/lib/base/math-script.cpp
index 7d96611a4..6cd7b0eb4 100644
--- a/lib/base/math-script.cpp
+++ b/lib/base/math-script.cpp
@@ -180,5 +180,5 @@ INITIALIZE_ONCE([]() {
 	mathNS->Freeze();
 
 	Namespace::Ptr systemNS = ScriptGlobal::Get("System");
-	systemNS->Set("Math", mathNS, true, true);
+	systemNS->Set("Math", mathNS, true);
 });
diff --git a/lib/base/namespace.cpp b/lib/base/namespace.cpp
index 729841cac..cb7c872bd 100644
--- a/lib/base/namespace.cpp
+++ b/lib/base/namespace.cpp
@@ -33,7 +33,7 @@ Value Namespace::Get(const String& field) const
 
 bool Namespace::Get(const String& field, Value *value) const
 {
-	std::shared_lock<decltype(m_DataMutex)> lock(m_DataMutex);
+	auto lock(ReadLockUnlessFrozen());
 
 	auto nsVal = m_Data.find(field);
 
@@ -45,21 +45,22 @@ bool Namespace::Get(const String& field, Value *value) const
 	return true;
 }
 
-void Namespace::Set(const String& field, const Value& value, bool isConst, bool overrideFrozen, const DebugInfo& debugInfo)
+void Namespace::Set(const String& field, const Value& value, bool isConst, const DebugInfo& debugInfo)
 {
 	ObjectLock olock(this);
+
+	if (m_Frozen) {
+		BOOST_THROW_EXCEPTION(ScriptError("Namespace is read-only and must not be modified.", debugInfo));
+	}
+
 	std::unique_lock<decltype(m_DataMutex)> dlock (m_DataMutex);
 
 	auto nsVal = m_Data.find(field);
 
 	if (nsVal == m_Data.end()) {
-		if (m_Frozen && !overrideFrozen) {
-			BOOST_THROW_EXCEPTION(ScriptError("Namespace is read-only and must not be modified.", debugInfo));
-		}
-
 		m_Data[field] = NamespaceValue{value, isConst};
 	} else {
-		if (nsVal->second.Const && !overrideFrozen) {
+		if (nsVal->second.Const) {
 			BOOST_THROW_EXCEPTION(ScriptError("Constant must not be modified.", debugInfo));
 		}
 
@@ -74,46 +75,43 @@ void Namespace::Set(const String& field, const Value& value, bool isConst, bool
  */
 size_t Namespace::GetLength() const
 {
-	std::shared_lock<decltype(m_DataMutex)> lock(m_DataMutex);
+	auto lock(ReadLockUnlessFrozen());
 
 	return m_Data.size();
 }
 
 bool Namespace::Contains(const String& field) const
 {
-	std::shared_lock<decltype(m_DataMutex)> lock(m_DataMutex);
+	auto lock (ReadLockUnlessFrozen());
 
 	return m_Data.find(field) != m_Data.end();
 }
 
-void Namespace::Remove(const String& field, bool overrideFrozen)
+void Namespace::Remove(const String& field)
 {
 	ObjectLock olock(this);
 
-	if (m_Frozen && !overrideFrozen) {
+	if (m_Frozen) {
 		BOOST_THROW_EXCEPTION(ScriptError("Namespace is read-only and must not be modified."));
 	}
 
 	std::unique_lock<decltype(m_DataMutex)> dlock (m_DataMutex);
 
-	if (!overrideFrozen) {
-		auto attr = m_Data.find(field);
-
-		if (attr != m_Data.end() && attr->second.Const) {
-			BOOST_THROW_EXCEPTION(ScriptError("Constants must not be removed."));
-		}
-	}
-
 	auto it = m_Data.find(field);
 
-	if (it == m_Data.end())
+	if (it == m_Data.end()) {
 		return;
+	}
+
+	if (it->second.Const) {
+		BOOST_THROW_EXCEPTION(ScriptError("Constants must not be removed."));
+	}
 
 	m_Data.erase(it);
 }
 
 /**
- * Freeze the namespace, preventing further updates unless overrideFrozen is set.
+ * Freeze the namespace, preventing further updates.
  *
  * This only prevents inserting, replacing or deleting values from the namespace. This operation has no effect on
  * objects referenced by the values, these remain mutable if they were before.
@@ -124,9 +122,18 @@ void Namespace::Freeze() {
 	m_Frozen = true;
 }
 
+std::shared_lock<std::shared_timed_mutex> Namespace::ReadLockUnlessFrozen() const
+{
+	if (m_Frozen.load(std::memory_order_relaxed)) {
+		return std::shared_lock<std::shared_timed_mutex>();
+	} else {
+		return std::shared_lock<std::shared_timed_mutex>(m_DataMutex);
+	}
+}
+
 Value Namespace::GetFieldByName(const String& field, bool, const DebugInfo& debugInfo) const
 {
-	std::shared_lock<decltype(m_DataMutex)> lock(m_DataMutex);
+	auto lock (ReadLockUnlessFrozen());
 
 	auto nsVal = m_Data.find(field);
 
@@ -138,7 +145,12 @@ Value Namespace::GetFieldByName(const String& field, bool, const DebugInfo& debu
 
 void Namespace::SetFieldByName(const String& field, const Value& value, bool overrideFrozen, const DebugInfo& debugInfo)
 {
-	Set(field, value, false, overrideFrozen, debugInfo);
+	// The override frozen parameter is mandated by the interface but ignored here. If the namespace is frozen, this
+	// disables locking for read operations, so it must not be modified again to ensure the consistency of the internal
+	// data structures.
+	(void) overrideFrozen;
+
+	Set(field, value, false, debugInfo);
 }
 
 bool Namespace::HasOwnField(const String& field) const
diff --git a/lib/base/namespace.hpp b/lib/base/namespace.hpp
index f643d9661..94f2055d3 100644
--- a/lib/base/namespace.hpp
+++ b/lib/base/namespace.hpp
@@ -8,6 +8,7 @@
 #include "base/shared-object.hpp"
 #include "base/value.hpp"
 #include "base/debuginfo.hpp"
+#include <atomic>
 #include <map>
 #include <vector>
 #include <memory>
@@ -68,9 +69,9 @@ public:
 
 	Value Get(const String& field) const;
 	bool Get(const String& field, Value *value) const;
-	void Set(const String& field, const Value& value, bool isConst = false, bool overrideFrozen = false, const DebugInfo& debugInfo = DebugInfo());
+	void Set(const String& field, const Value& value, bool isConst = false, const DebugInfo& debugInfo = DebugInfo());
 	bool Contains(const String& field) const;
-	void Remove(const String& field, bool overrideFrozen = false);
+	void Remove(const String& field);
 	void Freeze();
 
 	Iterator Begin();
@@ -86,10 +87,12 @@ public:
 	static Object::Ptr GetPrototype();
 
 private:
+	std::shared_lock<std::shared_timed_mutex> ReadLockUnlessFrozen() const;
+
 	std::map<String, NamespaceValue> m_Data;
 	mutable std::shared_timed_mutex m_DataMutex;
 	bool m_ConstValues;
-	bool m_Frozen;
+	std::atomic<bool> m_Frozen;
 };
 
 Namespace::Iterator begin(const Namespace::Ptr& x);
diff --git a/lib/base/scriptframe.cpp b/lib/base/scriptframe.cpp
index 4a67520ff..b9725cf60 100644
--- a/lib/base/scriptframe.cpp
+++ b/lib/base/scriptframe.cpp
@@ -29,18 +29,18 @@ INITIALIZE_ONCE_WITH_PRIORITY([]() {
 	l_SystemNS->Set("BuildHostName", ICINGA_BUILD_HOST_NAME);
 	l_SystemNS->Set("BuildCompilerName", ICINGA_BUILD_COMPILER_NAME);
 	l_SystemNS->Set("BuildCompilerVersion", ICINGA_BUILD_COMPILER_VERSION);
-	globalNS->Set("System", l_SystemNS, false, true);
+	globalNS->Set("System", l_SystemNS, true);
 
-	l_SystemNS->Set("Configuration", new Configuration(), false, true);
+	l_SystemNS->Set("Configuration", new Configuration());
 
 	l_TypesNS = new Namespace(true);
-	globalNS->Set("Types", l_TypesNS, false, true);
+	globalNS->Set("Types", l_TypesNS, true);
 
 	l_StatsNS = new Namespace(true);
-	globalNS->Set("StatsFunctions", l_StatsNS, false, true);
+	globalNS->Set("StatsFunctions", l_StatsNS, true);
 
 	l_InternalNS = new Namespace(true);
-	globalNS->Set("Internal", l_InternalNS, false, true);
+	globalNS->Set("Internal", l_InternalNS, true);
 }, InitializePriority::CreateNamespaces);
 
 INITIALIZE_ONCE_WITH_PRIORITY([]() {
diff --git a/lib/icinga/icingaapplication.cpp b/lib/icinga/icingaapplication.cpp
index 1e554f3ff..c20ee4cfb 100644
--- a/lib/icinga/icingaapplication.cpp
+++ b/lib/icinga/icingaapplication.cpp
@@ -54,8 +54,8 @@ void IcingaApplication::StaticInitialize()
 	/* Ensure that the System namespace is already initialized. Otherwise this is a programming error. */
 	VERIFY(systemNS);
 
-	systemNS->Set("ApplicationType", "IcingaApplication", false, true);
-	systemNS->Set("ApplicationVersion", Application::GetAppVersion(), false, true);
+	systemNS->Set("ApplicationType", "IcingaApplication", true);
+	systemNS->Set("ApplicationVersion", Application::GetAppVersion(), true);
 
 	Namespace::Ptr globalNS = ScriptGlobal::GetGlobals();
 	VERIFY(globalNS);