diff --git a/src/env_base.cpp b/src/env_base.cpp
index 453904f..33a4cac 100644
--- a/src/env_base.cpp
+++ b/src/env_base.cpp
@@ -92,6 +92,21 @@ void EnvBase::set (std::string_view name, std::string_view value) {
 	this->set_implem(name, value, m);
 }
 
+void EnvBase::unset (std::string_view name) noexcept {
+	StdMutex m(this->mutex());
+	call_noexcept([&,this](){this->unset_implem(name, m);}, to_string_view(__func__));
+}
+
+bool EnvBase::is_set (std::string_view name) const noexcept {
+	StdMutex m(this->mutex());
+	return call_noexcept([&,this](){return this->is_set_implem(name, m);}, to_string_view(__func__));
+}
+
+auto EnvBase::size() const noexcept -> size_type {
+	StdMutex m(this->mutex());
+	return call_noexcept([this,&m](){return this->size_implem(m);}, to_string_view(__func__));
+}
+
 void EnvBase::set_nolock (EnvBase& obj, std::string_view name, std::string_view value) {
 	EmptyMutex m;
 	obj.set_implem(name, value, m);
diff --git a/src/env_base.hpp b/src/env_base.hpp
index eeeeba0..2567597 100644
--- a/src/env_base.hpp
+++ b/src/env_base.hpp
@@ -68,21 +68,26 @@ namespace duck {
 		virtual std::optional<std::string_view> get (std::string_view name) const noexcept = 0;
 		virtual std::string_view get (std::string_view name, std::string_view def) const noexcept = 0;
 		void set (std::string_view name, std::string_view value);
-		virtual void unset (std::string_view name) noexcept = 0;
-		virtual bool is_set (std::string_view name) const noexcept = 0;
-		virtual size_type size() const noexcept = 0;
-		virtual bool empty() const noexcept;
+		void unset (std::string_view name) noexcept;
+		bool is_set (std::string_view name) const noexcept;
+		size_type size() const noexcept;
+		bool empty() const noexcept;
 		void clear() noexcept;
 
-		virtual std::mutex& mutex() noexcept = 0;
+		virtual std::mutex& mutex() const noexcept = 0;
 
 	protected:
 		virtual void set_all_into (EnvBase& other) const = 0;
 		static void set_all_into (const EnvBase& obj, EnvBase& other) { obj.set_all_into(other); }
 		virtual void clear_implem(Mutex& m) = 0;
 		static void clear_nolock (EnvBase& obj) noexcept;
+
 		virtual void set_implem (std::string_view name, std::string_view value, Mutex& m) = 0;
 		static void set_nolock (EnvBase& obj, std::string_view name, std::string_view value);
+
+		virtual void unset_implem (std::string_view name, Mutex& m) = 0;
+		virtual bool is_set_implem (std::string_view name, Mutex& m) const = 0;
+		virtual size_type size_implem(Mutex& m) const = 0;
 	};
 
 	namespace detail {
diff --git a/src/env_fake.cpp b/src/env_fake.cpp
index 05b85e8..169d3fa 100644
--- a/src/env_fake.cpp
+++ b/src/env_fake.cpp
@@ -111,16 +111,19 @@ void EnvFake::set_implem (std::string_view name, std::string_view value, Mutex&
 	}
 }
 
-void EnvFake::unset (std::string_view name) noexcept {
+void EnvFake::unset_implem (std::string_view name, Mutex& m) {
+	std::lock_guard<Mutex> lock(m);
 	run_if_found(m_map, name, [&](auto& it)noexcept{m_map.erase(it);});
 	run_if_found(m_map_strong_cpy, name, [&](auto& it)noexcept{m_map_strong_cpy.erase(it);});
 }
 
-bool EnvFake::is_set (std::string_view name) const noexcept {
+bool EnvFake::is_set_implem (std::string_view name, Mutex& m) const {
+	std::lock_guard<Mutex> lock(m);
 	return run_if_found(m_map, name, [](auto&)noexcept{return true;});
 }
 
-auto EnvFake::size() const noexcept -> size_type {
+auto EnvFake::size_implem (Mutex& m) const -> size_type {
+	std::lock_guard<Mutex> lock(m);
 	return m_map.size();
 }
 
@@ -146,7 +149,7 @@ auto EnvFake::cend() const -> const_iterator {
 	return m_map.cend();
 }
 
-std::mutex& EnvFake::mutex() noexcept {
+std::mutex& EnvFake::mutex() const noexcept {
 	return m_mutex;
 }
 
diff --git a/src/env_fake.hpp b/src/env_fake.hpp
index 236004d..5de66e9 100644
--- a/src/env_fake.hpp
+++ b/src/env_fake.hpp
@@ -35,21 +35,21 @@ namespace duck {
 
 		virtual std::optional<std::string_view> get (std::string_view name) const noexcept override;
 		virtual std::string_view get (std::string_view name, std::string_view def) const noexcept override;
-		virtual void unset (std::string_view name) noexcept override;
-		virtual bool is_set (std::string_view name) const noexcept override;
-		virtual size_type size() const noexcept override;
 
 		const_iterator begin() const;
 		const_iterator cbegin() const;
 		const_iterator end() const;
 		const_iterator cend() const;
 
-		virtual std::mutex& mutex() noexcept override;
+		virtual std::mutex& mutex() const noexcept override;
 
 	protected:
 		virtual void set_all_into (EnvBase& other) const override;
 		virtual void clear_implem(Mutex& m) override;
 		virtual void set_implem (std::string_view name, std::string_view value, Mutex& m) override;
+		virtual void unset_implem (std::string_view name, Mutex& m) override;
+		virtual bool is_set_implem (std::string_view name, Mutex& m) const override;
+		virtual size_type size_implem (Mutex& m) const override;
 
 	private:
 		std::unordered_map<std::string_view, std::unique_ptr<char[]>> m_map_strong_cpy;
diff --git a/src/env_real.cpp b/src/env_real.cpp
index 63d7933..9d6ce4e 100644
--- a/src/env_real.cpp
+++ b/src/env_real.cpp
@@ -246,9 +246,9 @@ void EnvReal::set_implem (std::string_view name, std::string_view value, Mutex&
 	}
 }
 
-void EnvReal::unset (std::string_view name) noexcept {
+void EnvReal::unset_implem (std::string_view name, Mutex& m) {
 	auto& pm = pointer_map();
-	std::lock_guard<std::mutex> lock(pm.env_mutex());
+	std::lock_guard<Mutex> lock(m);
 
 	duck::invoke_with_zstr(
 		name,
@@ -262,9 +262,8 @@ void EnvReal::unset (std::string_view name) noexcept {
 	);
 }
 
-bool EnvReal::is_set (std::string_view name) const noexcept {
-	auto& pm = pointer_map();
-	std::lock_guard<std::mutex> lock(pm.env_mutex());
+bool EnvReal::is_set_implem (std::string_view name, Mutex& m) const {
+	std::lock_guard<Mutex> lock(m);
 
 	return duck::invoke_with_zstr(
 		name,
@@ -276,9 +275,8 @@ bool EnvReal::is_set (std::string_view name) const noexcept {
 	);
 }
 
-auto EnvReal::size() const noexcept -> size_type {
-	auto& pm = pointer_map();
-	std::lock_guard<std::mutex> lock(pm.env_mutex());
+auto EnvReal::size_implem (Mutex& m) const -> size_type {
+	std::lock_guard<Mutex> lock(m);
 
 	assert(environ);
 	size_type z = 0;
@@ -332,7 +330,7 @@ auto EnvReal::cend() const -> const_iterator {
 	return {::environ + this->size()};
 }
 
-std::mutex& EnvReal::mutex() noexcept {
+std::mutex& EnvReal::mutex() const noexcept {
 	return pointer_map().env_mutex();
 }
 
diff --git a/src/env_real.hpp b/src/env_real.hpp
index 72ff5d3..9e61022 100644
--- a/src/env_real.hpp
+++ b/src/env_real.hpp
@@ -56,21 +56,21 @@ namespace duck {
 
 		virtual std::optional<std::string_view> get (std::string_view name) const noexcept override;
 		virtual std::string_view get (std::string_view name, std::string_view def) const noexcept override;
-		virtual void unset (std::string_view name) noexcept override;
-		virtual bool is_set (std::string_view name) const noexcept override;
-		virtual size_type size() const noexcept override;
 
 		const_iterator begin() const;
 		const_iterator cbegin() const;
 		const_iterator end() const;
 		const_iterator cend() const;
 
-		virtual std::mutex& mutex() noexcept override;
+		virtual std::mutex& mutex() const noexcept override;
 
 	protected:
 		virtual void set_all_into (EnvBase& other) const override;
 		virtual void clear_implem(Mutex& m) override;
 		virtual void set_implem (std::string_view name, std::string_view value, Mutex& m) override;
+		virtual void unset_implem (std::string_view name, Mutex& m) override;
+		virtual bool is_set_implem (std::string_view name, Mutex& m) const override;
+		virtual size_type size_implem(Mutex& m) const override;
 
 	private:
 		const char* raw_fetch_env (std::string_view name) const noexcept;