diff --git a/.github/workflows/linux-ci.yml b/.github/workflows/linux-ci.yml
index 452c4d4..0c13588 100644
--- a/.github/workflows/linux-ci.yml
+++ b/.github/workflows/linux-ci.yml
@@ -9,7 +9,7 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v2
diff --git a/.github/workflows/mac-ci.yml b/.github/workflows/mac-ci.yml
index 3f75a7a..5a7d668 100644
--- a/.github/workflows/mac-ci.yml
+++ b/.github/workflows/mac-ci.yml
@@ -9,7 +9,7 @@ on:
 jobs:
   build:
 
-    runs-on: macos-latest
+    runs-on: macos-11
 
     steps:
     - uses: actions/checkout@v2
@@ -18,8 +18,8 @@ jobs:
         brew update
         brew install tcl-tk || true
         sudo mkdir -p /usr/local
-        sudo ln -sf /usr/local/opt/tcl-tk/include /usr/local/include/tcl8.6
-        sudo cp /usr/local/opt/tcl-tk/lib/libtcl* /usr/local/lib
+        sudo ln -sf /usr/local/opt/tcl-tk/include/tcl-tk /usr/local/include/tcl8.6
+        sudo install /usr/local/opt/tcl-tk/lib/libtcl* /usr/local/lib
         sudo ln -sf /usr/local/opt/tcl-tk/bin/tclsh8.6 /usr/local/bin/tclsh
         sudo ln -sf /usr/local/opt/tcl-tk/bin/tclsh8.6 /usr/local/bin/tclsh8.6
     - name: make
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d2741e5..1ad5c84 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,7 +5,7 @@ project(cpptcl)
 include(cmake/version.cmake)
 load_git_properties(cpptcl ${CMAKE_BINARY_DIR}/generated)
 
-set(CPPTCL_VERSION 2.2.5)
+set(CPPTCL_VERSION 2.2.8)
 
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   message(STATUS "Setting build type to Release as none was specified.")
diff --git a/cpptcl/cpptcl.h b/cpptcl/cpptcl.h
index 7a748d6..1852a6c 100644
--- a/cpptcl/cpptcl.h
+++ b/cpptcl/cpptcl.h
@@ -110,12 +110,20 @@ void set_result(Tcl_Interp *interp, std::string const &s);
 void set_result(Tcl_Interp *interp, void *p);
 void set_result(Tcl_Interp *interp, object const &o);
 
+}
+
+}
+
 // helper functor for converting Tcl objects to the given type
 #include "cpptcl/details/conversions.h"
 
 // dispatchers able to capture (or ignore) the result
 #include "cpptcl/details/dispatchers.h"
 
+namespace Tcl {
+
+namespace details {
+
 // helper for checking for required number of parameters
 // (throws tcl_error when not met)
 void check_params_no(int objc, int required, const std::string &message);
@@ -123,7 +131,7 @@ void check_params_no(int objc, int required, const std::string &message);
 // helper for gathering optional params in variadic functions
 object get_var_params(Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[], int from, policies const &pol);
 
-// the callback_base is used to store callback handlers in a polynorphic map
+// the callback_base is used to store callback handlers in a polymorphic map
 class callback_base {
   public:
 	virtual ~callback_base() {}
@@ -190,6 +198,10 @@ template <class C> class class_handler : public class_handler_base {
 	}
 };
 
+}
+
+}
+
 // factory functions for creating class objects
 #include "cpptcl/details/constructors.h"
 
@@ -202,6 +214,10 @@ template <class C> class class_handler : public class_handler_base {
 // helper meta function for figuring appropriate constructor callback
 #include "cpptcl/details/metahelpers.h"
 
+namespace Tcl {
+
+namespace details {
+
 // this class is used to provide the "def" interface for defining
 // class member functions
 
@@ -444,8 +460,12 @@ class interpreter {
 	bool owner_;
 };
 
+}
+
 #include "cpptcl/cpptcl_object.h"
 
+namespace Tcl {
+
 // the InputIterator should give object& or Tcl_Obj* when dereferenced
 template <class InputIterator> details::result interpreter::eval(InputIterator first, InputIterator last) {
 	std::vector<Tcl_Obj *> v;
@@ -458,7 +478,7 @@ template <class InputIterator> details::result interpreter::eval(InputIterator f
 	return details::result(interp_);
 }
 
-namespace details {
+}
 
 // additional callback envelopes for variadic functions
 #include "cpptcl/details/callbacks_v.h"
@@ -466,10 +486,11 @@ namespace details {
 // additional method envelopes for variadic methods
 #include "cpptcl/details/methods_v.h"
 
-} // namespace details
 
 #include "cpptcl/details/bind.h"
 
+namespace Tcl {
+
 inline std::ostream & operator<<(std::ostream &os, const object& obj)
 {
     return os << obj.get<std::string>();
diff --git a/cpptcl/cpptcl_object.h b/cpptcl/cpptcl_object.h
index 2d8cb18..a1f54ac 100644
--- a/cpptcl/cpptcl_object.h
+++ b/cpptcl/cpptcl_object.h
@@ -8,6 +8,8 @@
 #ifndef CPPTCL_OBJECT_H
 #define CPPTCL_OBJECT_H
 
+namespace Tcl {
+
 class object;
 
 /*
@@ -243,4 +245,6 @@ template <> char const *object::get<char const *>(interpreter &i) const;
 template <> std::string object::get<std::string>(interpreter &i) const;
 template <> std::vector<char> object::get<std::vector<char>>(interpreter &i) const;
 
+}
+
 #endif /* CPPTCL_OBJECT_H */
diff --git a/cpptcl/details/bind.h b/cpptcl/details/bind.h
index f731c4e..a66414f 100644
--- a/cpptcl/details/bind.h
+++ b/cpptcl/details/bind.h
@@ -1,3 +1,5 @@
+namespace Tcl {
+
 template <typename R, typename T1, typename T2 = void, typename T3 = void, typename T4 = void, typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, typename T9 = void> struct Bind {
   private:
 	object cmd_;
@@ -173,3 +175,5 @@ template <typename R> struct Bind<R, void, void, void, void, void, void, void, v
 		return (R)(interpreter::getDefault()->eval(obj));
 	}
 };
+
+}
diff --git a/cpptcl/details/callbacks.h b/cpptcl/details/callbacks.h
index ac60f01..e06902e 100644
--- a/cpptcl/details/callbacks.h
+++ b/cpptcl/details/callbacks.h
@@ -13,6 +13,8 @@
 #include <tuple>
 #include <utility>
 
+namespace Tcl { namespace details {
+
 template <typename R> class callback0 : public callback_base {
 	typedef R (*functor_type)();
 
@@ -213,3 +215,7 @@ template <typename R, typename T1, typename T2, typename T3, typename T4, typena
   private:
 	functor_type f_;
 };
+
+}
+
+}
diff --git a/cpptcl/details/callbacks_v.h b/cpptcl/details/callbacks_v.h
index 54d52f0..7fff7db 100644
--- a/cpptcl/details/callbacks_v.h
+++ b/cpptcl/details/callbacks_v.h
@@ -10,6 +10,8 @@
 
 // Note: this file is not supposed to be a stand-alone header
 
+namespace Tcl { namespace details {
+
 template <typename R> class callback1<R, object const &> : public callback_base {
 	typedef object const &T1;
 	typedef R (*functor_type)(T1);
@@ -199,3 +201,7 @@ template <typename R, typename T1, typename T2, typename T3, typename T4, typena
   private:
 	functor_type f_;
 };
+
+}
+
+}
diff --git a/cpptcl/details/constructors.h b/cpptcl/details/constructors.h
index 7ab5110..3aeef40 100644
--- a/cpptcl/details/constructors.h
+++ b/cpptcl/details/constructors.h
@@ -9,6 +9,7 @@
 //
 
 // Note: this file is not supposed to be a stand-alone header
+namespace Tcl { namespace details {
 
 template <class C, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9> struct construct {
 	static C *doit(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7, T8 t8, T9 t9) { return new C(t1, t2, t3, t4, t5, t6, t7, t8, t9); }
@@ -49,3 +50,7 @@ template <class C, typename T1> struct construct<C, T1, void, void, void, void,
 template <class C> struct construct<C, void, void, void, void, void, void, void, void, void> {
 	static C *doit() { return new C(); }
 };
+
+}
+
+}
diff --git a/cpptcl/details/conversions.h b/cpptcl/details/conversions.h
index ff12740..6d1eaa8 100644
--- a/cpptcl/details/conversions.h
+++ b/cpptcl/details/conversions.h
@@ -13,6 +13,7 @@
 // helper functor for converting Tcl objects to the given type
 // (it is a struct instead of function,
 // because I need to partially specialize it)
+namespace Tcl { namespace details {
 
 template <typename T> struct tcl_cast;
 
@@ -65,3 +66,6 @@ template <> struct tcl_cast<char const *> { static char const *from(Tcl_Interp *
 
 template <> struct tcl_cast<object> { static object from(Tcl_Interp *, Tcl_Obj *, bool byReference = false); };
 
+}
+
+}
diff --git a/cpptcl/details/dispatchers.h b/cpptcl/details/dispatchers.h
index 9a1e93b..b1998b9 100644
--- a/cpptcl/details/dispatchers.h
+++ b/cpptcl/details/dispatchers.h
@@ -14,6 +14,8 @@
 // capture its return value
 // further dispatch<void> specialization ignores the res
 
+namespace Tcl { namespace details {
+
 template <typename R> struct dispatch {
 	template <class Functor> static void do_dispatch(Tcl_Interp *interp, Functor f) {
 		R res = f();
@@ -87,3 +89,7 @@ template <> struct dispatch<void> {
 
 	template <typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9, class Functor> static void do_dispatch(Tcl_Interp *, Functor f, T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7, T8 t8, T9 t9) { f(t1, t2, t3, t4, t5, t6, t7, t8, t9); }
 };
+
+}
+
+}
diff --git a/cpptcl/details/metahelpers.h b/cpptcl/details/metahelpers.h
index d87cfa8..b3436d7 100644
--- a/cpptcl/details/metahelpers.h
+++ b/cpptcl/details/metahelpers.h
@@ -9,6 +9,7 @@
 //
 
 // Note: this file is not supposed to be a stand-alone header
+namespace Tcl { namespace details {
 
 template <class C, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9> struct get_callback_type_for_construct { typedef callback9<C *, T1, T2, T3, T4, T5, T6, T7, T8, T9> type; };
 
@@ -29,3 +30,7 @@ template <class C, typename T1, typename T2> struct get_callback_type_for_constr
 template <class C, typename T1> struct get_callback_type_for_construct<C, T1, void, void, void, void, void, void, void, void> { typedef callback1<C *, T1> type; };
 
 template <class C> struct get_callback_type_for_construct<C, void, void, void, void, void, void, void, void, void> { typedef callback0<C *> type; };
+
+}
+
+}
diff --git a/cpptcl/details/methods.h b/cpptcl/details/methods.h
index 34029ff..ef33cd4 100644
--- a/cpptcl/details/methods.h
+++ b/cpptcl/details/methods.h
@@ -9,6 +9,7 @@
 //
 
 // Note: this file is not supposed to be a stand-alone header
+namespace Tcl { namespace details {
 
 template <class C, typename R> class method0 : public object_cmd_base {
 	typedef R (C::*mem_type)();
@@ -302,3 +303,7 @@ template <class C, typename R, typename T1, typename T2, typename T3, typename T
 	cmem_type cf_;
 	bool cmem_;
 };
+
+}
+
+}
diff --git a/cpptcl/details/methods_v.h b/cpptcl/details/methods_v.h
index 835dea8..2bd4c0d 100644
--- a/cpptcl/details/methods_v.h
+++ b/cpptcl/details/methods_v.h
@@ -9,6 +9,7 @@
 //
 
 // Note: this file is not supposed to be a stand-alone header
+namespace Tcl { namespace details {
 
 template <class C, typename R> class method1<C, R, object const &> : public object_cmd_base {
 	typedef object const &T1;
@@ -261,3 +262,7 @@ template <class C, typename R, typename T1, typename T2, typename T3, typename T
 	cmem_type cf_;
 	bool cmem_;
 };
+
+}
+
+}