diff --git a/src/TNL/CMakeLists.txt b/src/TNL/CMakeLists.txt
index da996f1968b5d824dd1f9af255961c925820fe3d..99362ccf29e48c6451f2f3d6dced9a6d8b2b1225 100644
--- a/src/TNL/CMakeLists.txt
+++ b/src/TNL/CMakeLists.txt
@@ -35,12 +35,12 @@ set( headers
      StaticFor.h
      String.h
      Timer.h
+     Timer_impl.h
      StaticVectorFor.h )
 
 set( common_SOURCES
      FileName.cpp
-     String.cpp
-     Timer.cpp )
+     String.cpp )
 
 set( tnl_SOURCES ${tnl_config_SOURCES}
                  ${tnl_containers_SOURCES}
diff --git a/src/TNL/Timer.h b/src/TNL/Timer.h
index 530dcae216e7241c7ecf4da90854992b366ca7b4..7f2331f185817ba42aa84b3f36e8c0ce9a0dbae5 100644
--- a/src/TNL/Timer.h
+++ b/src/TNL/Timer.h
@@ -132,7 +132,6 @@ class Timer
    }
 };
 
-extern Timer defaultTimer;
-
 } // namespace TNL
 
+#include <TNL/Timer_impl.h>
diff --git a/src/TNL/Timer.cpp b/src/TNL/Timer_impl.h
similarity index 80%
rename from src/TNL/Timer.cpp
rename to src/TNL/Timer_impl.h
index e3649367247fcb46cfb084a2990c49cd7623509d..5a1cec336efcb1b226949064a62a9f573eb1ee61 100644
--- a/src/TNL/Timer.cpp
+++ b/src/TNL/Timer_impl.h
@@ -1,5 +1,5 @@
 /***************************************************************************
-                          Timer.cpp  -  description
+                          Timer_impl.h  -  description
                              -------------------
     begin                : Mar 14, 2016
     copyright            : (C) 2016 by Tomas Oberhuber
@@ -8,6 +8,8 @@
 
 /* See Copyright Notice in tnl/Copyright */
 
+#pragma once
+
 #include <TNL/Timer.h>
 #include <TNL/Logger.h>
 
@@ -19,14 +21,12 @@
 
 namespace TNL {
 
-Timer defaultTimer;
-
-Timer::Timer()
+inline Timer::Timer()
 {
    reset();
 }
 
-void Timer::reset()
+inline void Timer::reset()
 {
    this->initialCPUTime = 0;
    this->totalCPUTime = 0.0;
@@ -37,7 +37,7 @@ void Timer::reset()
    this->stopState = true;
 }
 
-void Timer::stop()
+inline void Timer::stop()
 {
 
    if( ! this->stopState )
@@ -49,7 +49,7 @@ void Timer::stop()
    }
 }
 
-void Timer::start()
+inline void Timer::start()
 {
    this->initialRealTime = this->readRealTime();
    this->initialCPUTime = this->readCPUTime();
@@ -57,33 +57,33 @@ void Timer::start()
    this->stopState = false;
 }
 
-double Timer::getRealTime() const
+inline double Timer::getRealTime() const
 {
    if( ! this->stopState )
       return durationToDouble( this->readRealTime() - this->initialRealTime );
    return durationToDouble( this->totalRealTime );
 }
 
-double Timer::getCPUTime() const
+inline double Timer::getCPUTime() const
 {
    if( ! this->stopState )
       return this->readCPUTime() - this->initialCPUTime;
    return this->totalCPUTime;
 }
 
-unsigned long long int Timer::getCPUCycles() const
+inline unsigned long long int Timer::getCPUCycles() const
 {
    if( ! this->stopState )
       return this->readCPUCycles() - this->initialCPUCycles;
    return this->totalCPUCycles;
 }
 
-typename Timer::TimePoint Timer::readRealTime() const
+inline typename Timer::TimePoint Timer::readRealTime() const
 {
    return std::chrono::high_resolution_clock::now();
 }
 
-double Timer::readCPUTime() const
+inline double Timer::readCPUTime() const
 {
 #if !defined(_WIN32) && !defined(_WIN64)
    rusage initUsage;
@@ -94,19 +94,19 @@ double Timer::readCPUTime() const
 #endif
 }
 
-unsigned long long int Timer::readCPUCycles() const
+inline unsigned long long int Timer::readCPUCycles() const
 {
    return this->rdtsc();
 }
 
-double Timer::durationToDouble( const Duration& duration ) const
+inline double Timer::durationToDouble( const Duration& duration ) const
 {
    std::chrono::duration< double > dur( duration );
    return dur.count();
 }
 
 
-bool Timer::writeLog( Logger& logger, int logLevel ) const
+inline bool Timer::writeLog( Logger& logger, int logLevel ) const
 {
    logger.writeParameter< double                 >( "Real time:",  this->getRealTime(),  logLevel );
    logger.writeParameter< double                 >( "CPU time:",   this->getCPUTime(),   logLevel );